[svn-r25555] - rework the public H5VL wrappers to not use H5VL_t* and use a plugin hid_t instead

- rework the private VL layer to use the class structure directly
- some bug fixes

30 files changed, 1218 insertions, 1035 deletions

diff --git a/examples/h5_vol_external_log_native.c b/examples/h5_vol_external_log_native.c
index d563441..5cc2593 100644
--- a/examples/h5_vol_external_log_native.c
+++ b/examples/h5_vol_external_log_native.c
@@ -40,6 +40,8 @@ static herr_t H5VL_log_group_close(void *grp, hid_t dxpl_id, void **req);
 static void *H5VL_log_object_open(void *obj, H5VL_loc_params_t loc_params, H5I_type_t *opened_type, hid_t dxpl_id, void **req);

 static herr_t H5VL_log_object_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_object_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments);

 

+hid_t native_plugin_id = -1;

+

 static const H5VL_class_t H5VL_log_g = {

     LOG,

     "log",					/* name */

@@ -117,7 +119,6 @@ static const H5VL_class_t H5VL_log_g = {
 

 typedef struct H5VL_log_t {

     void   *under_object;

-    H5VL_t *under_plugin;

 } H5VL_log_t;

 

 static herr_t

@@ -164,13 +165,19 @@ int main(int argc, char **argv) {
 

         under_fapl = H5Pcreate (H5P_FILE_ACCESS);

         H5Pset_fapl_native(under_fapl);

+        assert(H5VLis_registered("native") == 1);

+

         vol_id = H5VLregister (&H5VL_log_g);

-        assert(H5VLis_registered(&H5VL_log_g) == 1);

+        assert(vol_id > 0);

+        assert(H5VLis_registered("log") == 1);

 

-        vol_id2 = H5VLget_plugin_id(&H5VL_log_g);

+        vol_id2 = H5VLget_plugin_id("log");

         H5VLinitialize(vol_id2, H5P_DEFAULT);

         H5VLclose(vol_id2);

 

+        native_plugin_id = H5VLget_plugin_id("native");

+        assert(native_plugin_id > 0);

+

         acc_tpl = H5Pcreate (H5P_FILE_ACCESS);

         H5Pset_vol(acc_tpl, vol_id, &under_fapl);

 

@@ -248,9 +255,10 @@ int main(int argc, char **argv) {
         H5Pclose(acc_tpl);

         H5Pclose(under_fapl);

 

+        H5VLclose(native_plugin_id);

         H5VLterminate(vol_id, H5P_DEFAULT);

         H5VLunregister (vol_id);

-        assert(H5VLis_registered(&H5VL_log_g) == 0);

+        assert(H5VLis_registered("log") == 0);

 	return 0;

 }

 

@@ -275,7 +283,7 @@ H5VL_log_file_create(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl
     file = (H5VL_log_t *)calloc(1, sizeof(H5VL_log_t));

 

     under_fapl = *((hid_t *)H5Pget_vol_info(fapl_id));

-    file->under_object = H5VLfile_create(&(file->under_plugin), name, flags, fcpl_id, under_fapl, dxpl_id, req);

+    file->under_object = H5VLfile_create(name, flags, fcpl_id, under_fapl, dxpl_id, req);

 

     printf("------- LOG H5Fcreate\n");

     return (void *)file;

@@ -290,7 +298,7 @@ H5VL_log_file_open(const char *name, unsigned flags, hid_t fapl_id, hid_t dxpl_i
     file = (H5VL_log_t *)calloc(1, sizeof(H5VL_log_t));

 

     under_fapl = *((hid_t *)H5Pget_vol_info(fapl_id));

-    file->under_object = H5VLfile_open(&(file->under_plugin), name, flags, under_fapl, dxpl_id, req);

+    file->under_object = H5VLfile_open(name, flags, under_fapl, dxpl_id, req);

 

     printf("------- LOG H5Fopen\n");

     return (void *)file;

@@ -301,7 +309,7 @@ H5VL_log_file_get(void *file, H5VL_file_get_t get_type, hid_t dxpl_id, void **re
 {

     H5VL_log_t *f = (H5VL_log_t *)file;

 

-    H5VLfile_get(f->under_object, f->under_plugin, get_type, dxpl_id, req, arguments);

+    H5VLfile_get(f->under_object, native_plugin_id, get_type, dxpl_id, req, arguments);

 

     printf("------- LOG H5Fget %d\n", get_type);

     return 1;

@@ -311,7 +319,7 @@ H5VL_log_file_close(void *file, hid_t dxpl_id, void **req)
 {

     H5VL_log_t *f = (H5VL_log_t *)file;

 

-    H5VLfile_close(f->under_object, f->under_plugin, dxpl_id, req);

+    H5VLfile_close(f->under_object, native_plugin_id, dxpl_id, req);

     free(f);

 

     printf("------- LOG H5Fclose\n");

@@ -327,8 +335,7 @@ H5VL_log_group_create(void *obj, H5VL_loc_params_t loc_params, const char *name,
 

     group = (H5VL_log_t *)calloc(1, sizeof(H5VL_log_t));

 

-    group->under_object = H5VLgroup_create(o->under_object, loc_params, o->under_plugin, name, gcpl_id,  gapl_id, dxpl_id, req);

-    group->under_plugin = o->under_plugin;

+    group->under_object = H5VLgroup_create(o->under_object, loc_params, native_plugin_id, name, gcpl_id,  gapl_id, dxpl_id, req);

 

     printf("------- LOG H5Gcreate\n");

     return (void *)group;

@@ -339,7 +346,7 @@ H5VL_log_group_close(void *grp, hid_t dxpl_id, void **req)
 {

     H5VL_log_t *g = (H5VL_log_t *)grp;

 

-    H5VLgroup_close(g->under_object, g->under_plugin, dxpl_id, req);

+    H5VLgroup_close(g->under_object, native_plugin_id, dxpl_id, req);

     free(g);

 

     printf("------- LOG H5Gclose\n");

@@ -355,9 +362,8 @@ H5VL_log_datatype_commit(void *obj, H5VL_loc_params_t loc_params, const char *na
 

     dt = (H5VL_log_t *)calloc(1, sizeof(H5VL_log_t));

 

-    dt->under_object = H5VLdatatype_commit(o->under_object, loc_params, o->under_plugin, name, 

+    dt->under_object = H5VLdatatype_commit(o->under_object, loc_params, native_plugin_id, name, 

                                            type_id, lcpl_id, tcpl_id, tapl_id, dxpl_id, req);

-    dt->under_plugin = o->under_plugin;

 

     printf("------- LOG H5Tcommit\n");

     return dt;

@@ -370,8 +376,7 @@ H5VL_log_datatype_open(void *obj, H5VL_loc_params_t loc_params, const char *name
 

     dt = (H5VL_log_t *)calloc(1, sizeof(H5VL_log_t));

 

-    dt->under_object = H5VLdatatype_open(o->under_object, loc_params, o->under_plugin, name, tapl_id, dxpl_id, req);

-    dt->under_plugin = o->under_plugin;

+    dt->under_object = H5VLdatatype_open(o->under_object, loc_params, native_plugin_id, name, tapl_id, dxpl_id, req);

 

     printf("------- LOG H5Topen\n");

     return (void *)dt;

@@ -383,7 +388,7 @@ H5VL_log_datatype_get(void *dt, H5VL_datatype_get_t get_type, hid_t dxpl_id, voi
     H5VL_log_t *o = (H5VL_log_t *)dt;

     herr_t ret_value;

 

-    ret_value = H5VLdatatype_get(o->under_object, o->under_plugin, get_type, dxpl_id, req, arguments);

+    ret_value = H5VLdatatype_get(o->under_object, native_plugin_id, get_type, dxpl_id, req, arguments);

 

     printf("------- LOG datatype get\n");

     return ret_value;

@@ -395,9 +400,8 @@ H5VL_log_datatype_close(void *dt, hid_t dxpl_id, void **req)
     H5VL_log_t *type = (H5VL_log_t *)dt;

 

     assert(type->under_object);

-    assert(type->under_plugin);

 

-    H5VLdatatype_close(type->under_object, type->under_plugin, dxpl_id, req);

+    H5VLdatatype_close(type->under_object, native_plugin_id, dxpl_id, req);

     free(type);

 

     printf("------- LOG H5Tclose\n");

@@ -412,8 +416,7 @@ H5VL_log_object_open(void *obj, H5VL_loc_params_t loc_params, H5I_type_t *opened
 

     new_obj = (H5VL_log_t *)calloc(1, sizeof(H5VL_log_t));

     

-    new_obj->under_object = H5VLobject_open(o->under_object, loc_params, o->under_plugin, opened_type, dxpl_id, req);

-    new_obj->under_plugin = o->under_plugin;

+    new_obj->under_object = H5VLobject_open(o->under_object, loc_params, native_plugin_id, opened_type, dxpl_id, req);

 

     printf("------- LOG H5Oopen\n");

     return (void *)new_obj;

@@ -425,7 +428,7 @@ H5VL_log_object_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_object_sp
 {

     H5VL_log_t *o = (H5VL_log_t *)obj;

 

-    H5VLobject_specific(o->under_object, loc_params, o->under_plugin, specific_type, dxpl_id, req, arguments);

+    H5VLobject_specific(o->under_object, loc_params, native_plugin_id, specific_type, dxpl_id, req, arguments);

 

     printf("------- LOG Object specific\n");

     return 1;

@@ -439,8 +442,7 @@ H5VL_log_dataset_create(void *obj, H5VL_loc_params_t loc_params, const char *nam
 

     dset = (H5VL_log_t *)calloc(1, sizeof(H5VL_log_t));

 

-    dset->under_object = H5VLdataset_create(o->under_object, loc_params, o->under_plugin, name, dcpl_id,  dapl_id, dxpl_id, req);

-    dset->under_plugin = o->under_plugin;

+    dset->under_object = H5VLdataset_create(o->under_object, loc_params, native_plugin_id, name, dcpl_id,  dapl_id, dxpl_id, req);

 

     printf("------- LOG H5Dcreate\n");

     return (void *)dset;

@@ -454,8 +456,7 @@ H5VL_log_dataset_open(void *obj, H5VL_loc_params_t loc_params, const char *name,
 

     dset = (H5VL_log_t *)calloc(1, sizeof(H5VL_log_t));

 

-    dset->under_object = H5VLdataset_open(o->under_object, loc_params, o->under_plugin, name, dapl_id, dxpl_id, req);

-    dset->under_plugin = o->under_plugin;

+    dset->under_object = H5VLdataset_open(o->under_object, loc_params, native_plugin_id, name, dapl_id, dxpl_id, req);

 

     printf("------- LOG H5Dopen\n");

     return (void *)dset;

@@ -467,7 +468,7 @@ H5VL_log_dataset_read(void *dset, hid_t mem_type_id, hid_t mem_space_id,
 {

     H5VL_log_t *d = (H5VL_log_t *)dset;

 

-    H5VLdataset_read(d->under_object, d->under_plugin, mem_type_id, mem_space_id, file_space_id, 

+    H5VLdataset_read(d->under_object, native_plugin_id, mem_type_id, mem_space_id, file_space_id, 

                      plist_id, buf, req);

 

     printf("------- LOG H5Dread\n");

@@ -479,7 +480,7 @@ H5VL_log_dataset_write(void *dset, hid_t mem_type_id, hid_t mem_space_id,
 {

     H5VL_log_t *d = (H5VL_log_t *)dset;

 

-    H5VLdataset_write(d->under_object, d->under_plugin, mem_type_id, mem_space_id, file_space_id, 

+    H5VLdataset_write(d->under_object, native_plugin_id, mem_type_id, mem_space_id, file_space_id, 

                      plist_id, buf, req);

 

     printf("------- LOG H5Dwrite\n");

@@ -490,7 +491,7 @@ H5VL_log_dataset_close(void *dset, hid_t dxpl_id, void **req)
 {

     H5VL_log_t *d = (H5VL_log_t *)dset;

 

-    H5VLdataset_close(d->under_object, d->under_plugin, dxpl_id, req);

+    H5VLdataset_close(d->under_object, native_plugin_id, dxpl_id, req);

     free(d);

 

     printf("------- LOG H5Dclose\n");

diff --git a/src/H5A.c b/src/H5A.c
index 6b20c56..709a05f 100644
--- a/src/H5A.c
+++ b/src/H5A.c
@@ -274,17 +274,17 @@ H5Acreate2(hid_t loc_id, const char *attr_name, hid_t type_id, hid_t space_id,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_create(obj, loc_params, vol_plugin, attr_name, acpl_id, aapl_id, 
+    if(NULL == (attr = H5VL_attr_create(obj, loc_params, vol_plugin->cls, attr_name, acpl_id, aapl_id, 
                                         H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create attribute")
 
-    /* Get an atom for the attribute */
-    if((ret_value = H5I_register2(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
-	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attr handle")
+    /* Get an atom for the attribute with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
+	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize file handle")
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close(attr, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close(attr, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "unable to release attr")
 
     FUNC_LEAVE_API(ret_value)
@@ -374,17 +374,17 @@ H5Acreate_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_create(obj, loc_params, vol_plugin, attr_name, acpl_id, 
+    if(NULL == (attr = H5VL_attr_create(obj, loc_params, vol_plugin->cls, attr_name, acpl_id, 
                                         aapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create attribute")
 
-    /* Get an atom for the attribute */
-    if((ret_value = H5I_register2(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
-	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attr handle")
+    /* Get an atom for the attribute with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
+	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attribute handle")
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "unable to release attr")
     FUNC_LEAVE_API(ret_value)
 } /* H5Acreate_by_name() */
@@ -439,17 +439,17 @@ H5Aopen(hid_t loc_id, const char *attr_name, hid_t aapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin, attr_name, aapl_id, 
+    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin->cls, attr_name, aapl_id, 
                                       H5AC_ind_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open attribute")
 
-    /* Get an atom for the attribute */
-    if((ret_value = H5I_register2(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
-	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attr handle")
+    /* Get an atom for the attribute with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
+	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attribute handle")
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "unable to release attr")
     FUNC_LEAVE_API(ret_value)
 } /* H5Aopen() */
@@ -516,17 +516,17 @@ H5Aopen_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin, attr_name, aapl_id, 
+    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin->cls, attr_name, aapl_id, 
                                       H5AC_ind_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open attribute")
 
-    /* Get an atom for the attribute */
-    if((ret_value = H5I_register2(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
-	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attr handle")
+    /* Get an atom for the attribute with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
+	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attribute handle")
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "unable to release attr")
     FUNC_LEAVE_API(ret_value)
 } /* H5Aopen_by_name() */
@@ -602,17 +602,17 @@ H5Aopen_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin, NULL, aapl_id, 
+    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin->cls, NULL, aapl_id, 
                                       H5AC_ind_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open attribute")
 
-    /* Get an atom for the attribute */
-    if((ret_value = H5I_register2(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
-	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attr handle")
+    /* Get an atom for the attribute with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
+	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attribute handle")
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "unable to release attr")
     FUNC_LEAVE_API(ret_value)
 } /* H5Aopen_by_idx() */
@@ -655,7 +655,7 @@ H5Awrite(hid_t attr_id, hid_t dtype_id, const void *buf)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* write the data through the VOL */
-    if((ret_value = H5VL_attr_write(attr, vol_plugin, dtype_id, buf, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_attr_write(attr, vol_plugin->cls, dtype_id, buf, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_READERROR, FAIL, "can't read data")
 
 done:
@@ -700,7 +700,7 @@ H5Aread(hid_t attr_id, hid_t dtype_id, void *buf)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Read the data through the VOL */
-    if((ret_value = H5VL_attr_read(attr, vol_plugin, dtype_id, buf, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_attr_read(attr, vol_plugin->cls, dtype_id, buf, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_READERROR, FAIL, "can't read data")
 
 done:
@@ -743,7 +743,7 @@ H5Aget_space(hid_t attr_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* get the dataspace through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_SPACE, H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_attr_get(attr, vol_plugin->cls, H5VL_ATTR_GET_SPACE, H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get data space")
 
 done:
@@ -786,7 +786,7 @@ H5Aget_type(hid_t attr_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* get the datatype through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_TYPE, H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_attr_get(attr, vol_plugin->cls, H5VL_ATTR_GET_TYPE, H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get type")
 
 done:
@@ -834,7 +834,7 @@ H5Aget_create_plist(hid_t attr_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* get the acpl through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_ACPL, H5AC_dxpl_id, 
+    if(H5VL_attr_get(attr, vol_plugin->cls, H5VL_ATTR_GET_ACPL, H5AC_dxpl_id, 
                      H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get acpl")
 
@@ -889,7 +889,7 @@ H5Aget_name(hid_t attr_id, size_t buf_size, char *buf)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* get the name through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_NAME, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_attr_get(attr, vol_plugin->cls, H5VL_ATTR_GET_NAME, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                      loc_params, buf_size, buf, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get name")
 
@@ -960,7 +960,7 @@ H5Aget_name_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     loc_params.obj_type = H5I_get_type(loc_id);
 
     /* get the name through the VOL */
-    if(H5VL_attr_get(obj, vol_plugin, H5VL_ATTR_GET_NAME, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_attr_get(obj, vol_plugin->cls, H5VL_ATTR_GET_NAME, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                      loc_params, size, name, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get name")
 
@@ -1005,7 +1005,7 @@ H5Aget_storage_size(hid_t attr_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "ID does not contain VOL information")
 
     /* get the storage size through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_STORAGE_SIZE, H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_attr_get(attr, vol_plugin->cls, H5VL_ATTR_GET_STORAGE_SIZE, H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, 0, "unable to get acpl")
 
 done:
@@ -1049,7 +1049,7 @@ H5Aget_info(hid_t attr_id, H5A_info_t *ainfo)
     loc_params.obj_type = H5I_get_type(attr_id);
 
     /* get the attribute info through the VOL */
-    if(H5VL_attr_get(attr, vol_plugin, H5VL_ATTR_GET_INFO, H5AC_ind_dxpl_id, 
+    if(H5VL_attr_get(attr, vol_plugin->cls, H5VL_ATTR_GET_INFO, H5AC_ind_dxpl_id, 
                      H5_REQUEST_NULL, loc_params, ainfo) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get attribute info")
 
@@ -1111,7 +1111,7 @@ H5Aget_info_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* get the attribute info through the VOL */
-    if(H5VL_attr_get(obj, vol_plugin, H5VL_ATTR_GET_INFO, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_attr_get(obj, vol_plugin->cls, H5VL_ATTR_GET_INFO, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                      loc_params, ainfo, attr_name) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get attribute info")
 
@@ -1180,7 +1180,7 @@ H5Aget_info_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* get the attribute info through the VOL */
-    if(H5VL_attr_get(obj, vol_plugin, H5VL_ATTR_GET_INFO, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_attr_get(obj, vol_plugin->cls, H5VL_ATTR_GET_INFO, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                      loc_params, ainfo) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get attribute info")
 
@@ -1233,7 +1233,7 @@ H5Arename(hid_t loc_id, const char *old_name, const char *new_name)
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
         /* rename the attribute info through the VOL */
-        if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin, H5VL_ATTR_RENAME,
+        if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_RENAME,
                                            H5AC_dxpl_id, H5_REQUEST_NULL, old_name, new_name)) < 0)
             HGOTO_ERROR(H5E_ATTR, H5E_CANTRENAME, FAIL, "can't rename attribute")
     }
@@ -1299,7 +1299,7 @@ H5Arename_by_name(hid_t loc_id, const char *obj_name, const char *old_attr_name,
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
         /* rename the attribute info through the VOL */
-        if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin, H5VL_ATTR_RENAME,
+        if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_RENAME,
                                            H5AC_dxpl_id, H5_REQUEST_NULL, 
                                            old_attr_name, new_attr_name)) < 0)
             HGOTO_ERROR(H5E_ATTR, H5E_CANTRENAME, FAIL, "can't rename attribute")
@@ -1382,7 +1382,7 @@ H5Aiterate2(hid_t loc_id, H5_index_t idx_type, H5_iter_order_t order,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* iterate over the links through the VOL */
-    if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin, H5VL_ATTR_ITER,
+    if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_ITER,
                                        H5AC_dxpl_id, H5_REQUEST_NULL, 
                                        idx_type, order, idx, op, op_data)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_BADITER, FAIL, "attribute iteration failed")
@@ -1477,7 +1477,7 @@ H5Aiterate_by_name(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* iterate over the links through the VOL */
-    if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin, H5VL_ATTR_ITER,
+    if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_ITER,
                                        H5AC_dxpl_id, H5_REQUEST_NULL, 
                                        idx_type, order, idx, op, op_data)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_BADITER, FAIL, "attribute iteration failed")
@@ -1529,7 +1529,7 @@ H5Adelete(hid_t loc_id, const char *name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Delete the attribute through the VOL */
-    if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin, H5VL_ATTR_DELETE,
+    if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_DELETE,
                                        H5AC_dxpl_id, H5_REQUEST_NULL, name)) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_CANTDELETE, FAIL, "unable to delete attribute")
 
@@ -1592,7 +1592,7 @@ H5Adelete_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Delete the attribute through the VOL */
-    if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin, H5VL_ATTR_DELETE,
+    if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_DELETE,
                                        H5AC_dxpl_id, H5_REQUEST_NULL, attr_name)) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_CANTDELETE, FAIL, "unable to delete attribute")
 
@@ -1668,7 +1668,7 @@ H5Adelete_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Delete the attribute through the VOL */
-    if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin, H5VL_ATTR_DELETE,
+    if((ret_value = H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_DELETE,
                                        H5AC_dxpl_id, H5_REQUEST_NULL, NULL)) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_CANTDELETE, FAIL, "unable to delete attribute")
 
@@ -1755,7 +1755,7 @@ H5Aexists(hid_t obj_id, const char *attr_name)
     loc_params.obj_type = H5I_get_type(obj_id);
 
     /* Check existence of attribute through the VOL */
-    if(H5VL_attr_specific(obj, loc_params, vol_plugin, H5VL_ATTR_EXISTS,
+    if(H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_EXISTS,
                           H5AC_ind_dxpl_id, H5_REQUEST_NULL, attr_name, &ret_value) < 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTGET, FAIL, "unable to determine if attribute exists")
 done:
@@ -1814,7 +1814,7 @@ H5Aexists_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     loc_params.obj_type = H5I_get_type(loc_id);
 
     /* Check existence of attribute through the VOL */
-    if(H5VL_attr_specific(obj, loc_params, vol_plugin, H5VL_ATTR_EXISTS,
+    if(H5VL_attr_specific(obj, loc_params, vol_plugin->cls, H5VL_ATTR_EXISTS,
                           H5AC_ind_dxpl_id, H5_REQUEST_NULL, attr_name, &ret_value) < 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTGET, FAIL, "unable to determine if attribute exists")
 
@@ -1845,9 +1845,13 @@ H5A_close_attr(void *attr, H5VL_t *vol_plugin)
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Close the attr through the VOL*/
-    if((ret_value = H5VL_attr_close(attr, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_attr_close(attr, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_ATTR, H5E_CLOSEERROR, FAIL, "unable to close attribute")
 
+    /* decrement ref count on VOL ID */
+    if(H5VL_free_id(vol_plugin) < 0)
+	HGOTO_ERROR(H5E_ATTR, H5E_CANTDEC, FAIL, "unable to decrement ref count on VOL plugin")
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5A_close_attr() */
diff --git a/src/H5Adeprec.c b/src/H5Adeprec.c
index 24cee31..75d1665 100644
--- a/src/H5Adeprec.c
+++ b/src/H5Adeprec.c
@@ -205,16 +205,16 @@ H5Acreate1(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_create(obj, loc_params, vol_plugin, name, plist_id, H5P_DEFAULT, H5AC_dxpl_id, H5_REQUEST_NULL)))
+    if(NULL == (attr = H5VL_attr_create(obj, loc_params, vol_plugin->cls, name, plist_id, H5P_DEFAULT, H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create attribute")
 
-    /* Get an atom for the attribute */
-    if((ret_value = H5I_register2(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
-	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize dataset handle")
+    /* Get an atom for the attribute with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
+	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attribute handle")
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* H5Acreate1() */
@@ -272,17 +272,17 @@ H5Aopen_name(hid_t loc_id, const char *name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin, name, H5P_DEFAULT, 
+    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin->cls, name, H5P_DEFAULT, 
                                       H5AC_ind_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open attribute")
 
-    /* Get an atom for the attribute */
-    if((ret_value = H5I_register2(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
-	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize dataset handle")
+    /* Get an atom for the attribute with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
+	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attribute handle")
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* H5Aopen_name() */
@@ -342,17 +342,17 @@ H5Aopen_idx(hid_t loc_id, unsigned idx)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the attribute through the VOL */
-    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin, NULL, H5P_DEFAULT, 
+    if(NULL == (attr = H5VL_attr_open(obj, loc_params, vol_plugin->cls, NULL, H5P_DEFAULT, 
                                       H5AC_ind_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open attribute")
 
-    /* Get an atom for the attribute */
-    if((ret_value = H5I_register2(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
-	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize dataset handle")
+    /* Get an atom for the attribute with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_plugin, TRUE)) < 0)
+	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attribute handle")
 
 done:
     if (ret_value < 0 && attr)
-        if(H5VL_attr_close (attr, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_attr_close (attr, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* H5Aopen_idx() */
@@ -399,7 +399,7 @@ H5Aget_num_attrs(hid_t loc_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Get the group info through the VOL using the location token */
-    if(H5VL_object_optional(obj, vol_plugin, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_object_optional(obj, vol_plugin->cls, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                             H5VL_OBJECT_GET_INFO, loc_params, &oinfo) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
diff --git a/src/H5Aint.c b/src/H5Aint.c
index f67e6f4..b812d56 100644
--- a/src/H5Aint.c
+++ b/src/H5Aint.c
@@ -2468,20 +2468,6 @@ herr_t H5A_iterate(void *obj, H5VL_loc_params_t loc_params, H5_index_t idx_type,
     if(loc_params.type == H5VL_OBJECT_BY_SELF) {
         if((obj_loc_id = H5VL_native_register(loc_params.obj_type, obj, TRUE)) < 0)
             HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to register datatype")
-#if 0
-        /* Build the vol plugin struct */
-        if(NULL == (vol_plugin = (H5VL_t *)H5MM_calloc(sizeof(H5VL_t))))
-            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
-        vol_plugin->cls = &H5VL_native_g;
-        vol_plugin->nrefs = 1;
-        vol_plugin->id =  H5VL_NATIVE_g;
-        if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
-            HGOTO_ERROR(H5E_FILE, H5E_CANTINC, FAIL, "unable to increment ref count on VOL plugin")
-
-        /* Get an atom for the object */
-        if((obj_loc_id = H5I_register2(loc_params.obj_type, obj, vol_plugin, TRUE)) < 0)
-            HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to register object")
-#endif
     }
     else if(loc_params.type == H5VL_OBJECT_BY_NAME) { 
         /* Set up opened group location to fill in */
diff --git a/src/H5D.c b/src/H5D.c
index bd77414..2995a73 100644
--- a/src/H5D.c
+++ b/src/H5D.c
@@ -206,16 +206,16 @@ H5Dcreate2(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the dataset through the VOL */
-    if(NULL == (dset = H5VL_dataset_create(obj, loc_params, vol_plugin, name, dcpl_id, dapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)))
+    if(NULL == (dset = H5VL_dataset_create(obj, loc_params, vol_plugin->cls, name, dcpl_id, dapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to create dataset")
 
-    /* Get an atom for the dataset */
-    if((ret_value = H5I_register2(H5I_DATASET, dset, vol_plugin, TRUE)) < 0)
+    /* Get an atom for the dataset with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_DATASET, dset, vol_plugin, TRUE)) < 0)
 	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize dataset handle")
 
 done:
     if (ret_value < 0 && dset)
-        if(H5VL_dataset_close (dset, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_dataset_close (dset, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Dcreate2() */
@@ -306,16 +306,16 @@ H5Dcreate_anon(hid_t loc_id, hid_t type_id, hid_t space_id, hid_t dcpl_id,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the dataset through the VOL */
-    if(NULL == (dset = H5VL_dataset_create(obj, loc_params, vol_plugin, NULL, dcpl_id, dapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)))
+    if(NULL == (dset = H5VL_dataset_create(obj, loc_params, vol_plugin->cls, NULL, dcpl_id, dapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to create dataset")
 
-    /* Get an atom for the dataset */
-    if((ret_value = H5I_register2(H5I_DATASET, dset, vol_plugin, TRUE)) < 0)
+    /* Get an atom for the dataset with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_DATASET, dset, vol_plugin, TRUE)) < 0)
 	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize dataset handle")
 
 done:
     if (ret_value < 0 && dset)
-        if(H5VL_dataset_close (dset, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_dataset_close (dset, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Dcreate_anon() */
@@ -373,16 +373,16 @@ H5Dopen2(hid_t loc_id, const char *name, hid_t dapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the dataset through the VOL */
-    if(NULL == (dset = H5VL_dataset_open(obj, loc_params, vol_plugin, name, dapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)))
+    if(NULL == (dset = H5VL_dataset_open(obj, loc_params, vol_plugin->cls, name, dapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, FAIL, "unable to open dataset")
 
-    /* Get an atom for the dataset */
-    if((ret_value = H5I_register2(H5I_DATASET, dset, vol_plugin, TRUE)) < 0)
+    /* Get an atom for the dataset with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_DATASET, dset, vol_plugin, TRUE)) < 0)
 	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize dataset handle")
 
 done:
     if (ret_value < 0 && dset)
-        if(H5VL_dataset_close (dset, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_dataset_close (dset, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Dopen2() */
@@ -464,7 +464,7 @@ H5Dget_space(hid_t dset_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* get the dataspace through the VOL */
-    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_SPACE, H5AC_dxpl_id, 
+    if(H5VL_dataset_get(dset, vol_plugin->cls, H5VL_DATASET_GET_SPACE, H5AC_dxpl_id, 
 			H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get data space")
 
@@ -505,7 +505,7 @@ H5Dget_space_status(hid_t dset_id, H5D_space_status_t *allocation)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Read data space address through the VOL and return */
-    if((ret_value = H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_SPACE_STATUS, 
+    if((ret_value = H5VL_dataset_get(dset, vol_plugin->cls, H5VL_DATASET_GET_SPACE_STATUS, 
                                      H5AC_ind_dxpl_id, H5_REQUEST_NULL, allocation)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get space status")
 
@@ -548,7 +548,7 @@ H5Dget_type(hid_t dset_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* get the datatype through the VOL */
-    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_TYPE, H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_dataset_get(dset, vol_plugin->cls, H5VL_DATASET_GET_TYPE, H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get datatype")
 
 done:
@@ -589,7 +589,7 @@ H5Dget_create_plist(hid_t dset_id)
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(dset_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_DCPL, H5AC_dxpl_id, 
+    if(H5VL_dataset_get(dset, vol_plugin->cls, H5VL_DATASET_GET_DCPL, H5AC_dxpl_id, 
                         H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get dataset creation properties")
 
@@ -648,7 +648,7 @@ H5Dget_access_plist(hid_t dset_id)
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(dset_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_DAPL, H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_dataset_get(dset, vol_plugin->cls, H5VL_DATASET_GET_DAPL, H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get dataset access properties")
 
 done:
@@ -692,7 +692,7 @@ H5Dget_storage_size(hid_t dset_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "ID does not contain VOL information")
 
     /* get storage size through the VOL */
-    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_STORAGE_SIZE, 
+    if(H5VL_dataset_get(dset, vol_plugin->cls, H5VL_DATASET_GET_STORAGE_SIZE, 
                         H5AC_ind_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, 0, "unable to get storage size")
 
@@ -733,7 +733,7 @@ H5Dget_offset(hid_t dset_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, HADDR_UNDEF, "ID does not contain VOL information")
 
     /* get offset through the VOL */
-    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_OFFSET, H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_dataset_get(dset, vol_plugin->cls, H5VL_DATASET_GET_OFFSET, H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, HADDR_UNDEF, "unable to get offset")
 
 done:
@@ -934,13 +934,13 @@ H5Dvlen_get_buf_size(hid_t dataset_id, hid_t type_id, hid_t space_id,
 
     /* Save the dataset & VOL plugin */
     vlen_bufsize.dset = dset;
-    vlen_bufsize.vol_plugin = vol_plugin;
+    vlen_bufsize.vol_cls = vol_plugin->cls;
 
     vlen_bufsize.fspace_id = FAIL;
     vlen_bufsize.mspace_id = FAIL;
 
     /* Get a copy of the dataspace ID */
-    if(H5VL_dataset_get(dset, vol_plugin, H5VL_DATASET_GET_SPACE, H5AC_dxpl_id, 
+    if(H5VL_dataset_get(dset, vol_plugin->cls, H5VL_DATASET_GET_SPACE, H5AC_dxpl_id, 
 		        H5_REQUEST_NULL, &vlen_bufsize.fspace_id) < 0)
         HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, FAIL, "can't copy dataspace")
 
@@ -1035,7 +1035,7 @@ H5Dset_extent(hid_t dset_id, const hsize_t size[])
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* set the extent through the VOL */
-    if((ret_value = H5VL_dataset_specific(dset, vol_plugin, H5VL_DATASET_SET_EXTENT, 
+    if((ret_value = H5VL_dataset_specific(dset, vol_plugin->cls, H5VL_DATASET_SET_EXTENT, 
                                           H5AC_dxpl_id, H5_REQUEST_NULL, size)) < 0)
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to set extent of dataset")
 
@@ -1066,9 +1066,17 @@ H5D_close_dataset(void *dset, H5VL_t *vol_plugin)
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Close the dataset through the VOL */
-    if((ret_value = H5VL_dataset_close(dset, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_dataset_close(dset, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to close dataset")
 
 done:
+    /* MSC - Weird thing for datasets and filters:
+       Always decrement the ref count on the vol for datasets, since
+       the ID is removed even if the close fails */
+
+    /* decrement ref count on VOL ID */
+    if(H5VL_free_id(vol_plugin) < 0)
+	HGOTO_ERROR(H5E_DATASET, H5E_CANTDEC, FAIL, "unable to decrement ref count on VOL plugin")
+
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5D_close_dataset() */
diff --git a/src/H5Ddeprec.c b/src/H5Ddeprec.c
index 9df3317..6dd0ebb 100644
--- a/src/H5Ddeprec.c
+++ b/src/H5Ddeprec.c
@@ -206,17 +206,17 @@ H5Dcreate1(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the dataset through the VOL */
-    if(NULL == (dset = H5VL_dataset_create(obj, loc_params, vol_plugin, name, dcpl_id, 
+    if(NULL == (dset = H5VL_dataset_create(obj, loc_params, vol_plugin->cls, name, dcpl_id, 
                                            H5P_DATASET_ACCESS_DEFAULT, H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to create dataset")
 
-    /* Get an atom for the dataset */
-    if((ret_value = H5I_register2(H5I_DATASET, dset, vol_plugin, TRUE)) < 0)
+    /* Get an atom for the dataset with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_DATASET, dset, vol_plugin, TRUE)) < 0)
 	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize dataset handle")
 
 done:
     if (ret_value < 0 && dset)
-        if(H5VL_dataset_close (dset, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_dataset_close (dset, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Dcreate1() */
@@ -268,16 +268,16 @@ H5Dopen1(hid_t loc_id, const char *name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the dataset through the VOL */
-    if(NULL == (dset = H5VL_dataset_open(obj, loc_params, vol_plugin, name, dapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)))
+    if(NULL == (dset = H5VL_dataset_open(obj, loc_params, vol_plugin->cls, name, dapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to create dataset")
 
-    /* Get an atom for the dataset */
-    if((ret_value = H5I_register2(H5I_DATASET, dset, vol_plugin, TRUE)) < 0)
+    /* Get an atom for the dataset with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_DATASET, dset, vol_plugin, TRUE)) < 0)
 	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize dataset handle")
 
 done:
     if (ret_value < 0 && dset)
-        if(H5VL_dataset_close (dset, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_dataset_close (dset, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_DATASET, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Dopen1() */
diff --git a/src/H5Dint.c b/src/H5Dint.c
index 534a050..a1d062fa 100644
--- a/src/H5Dint.c
+++ b/src/H5Dint.c
@@ -2085,7 +2085,7 @@ H5D__vlen_get_buf_size(void UNUSED *elem, hid_t type_id, unsigned UNUSED ndim, c
         HGOTO_ERROR(H5E_DATASET, H5E_CANTCREATE, FAIL, "can't select point")
 
     /* Read in the point (with the custom VL memory allocator) */
-    if(H5VL_dataset_read(vlen_bufsize->dset, vlen_bufsize->vol_plugin, 
+    if(H5VL_dataset_read(vlen_bufsize->dset, vlen_bufsize->vol_cls, 
                          type_id, vlen_bufsize->mspace_id, 
                          vlen_bufsize->fspace_id, vlen_bufsize->xfer_pid, 
                          vlen_bufsize->fl_tbuf, H5_REQUEST_NULL) < 0)
diff --git a/src/H5Dio.c b/src/H5Dio.c
index c5bfb19..015e5e0 100644
--- a/src/H5Dio.c
+++ b/src/H5Dio.c
@@ -165,7 +165,7 @@ H5Dread(hid_t dset_id, hid_t mem_type_id, hid_t mem_space_id,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Read the data through the VOL */
-    if((ret_value = H5VL_dataset_read(dset, vol_plugin, mem_type_id, mem_space_id, 
+    if((ret_value = H5VL_dataset_read(dset, vol_plugin->cls, mem_type_id, mem_space_id, 
                                       file_space_id, plist_id, buf, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_DATASET, H5E_READERROR, FAIL, "can't read data")
 
@@ -268,7 +268,7 @@ H5Dwrite(hid_t dset_id, hid_t mem_type_id, hid_t mem_space_id,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Write the data through the VOL */
-    if((ret_value = H5VL_dataset_write(dset, vol_plugin, mem_type_id, mem_space_id, 
+    if((ret_value = H5VL_dataset_write(dset, vol_plugin->cls, mem_type_id, mem_space_id, 
                                        file_space_id, dxpl_id, buf, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "can't write data")
 
diff --git a/src/H5Dpkg.h b/src/H5Dpkg.h
index 9d828e4..86da45f 100644
--- a/src/H5Dpkg.h
+++ b/src/H5Dpkg.h
@@ -480,7 +480,7 @@ typedef struct H5D_fill_buf_info_t {
 /* Internal data structure for computing variable-length dataset's total size */
 typedef struct {
     void *dset;         /* Dataset for operation */
-    H5VL_t *vol_plugin; /* VOL plugin the dataset belongs to */
+    const H5VL_class_t *vol_cls; /* VOL plugin the dataset belongs to */
     hid_t fspace_id;    /* ID of the file dataset's dataspace we are working on */
     hid_t mspace_id;    /* ID of the memory dataset's dataspace we are working on */
     void *fl_tbuf;      /* Ptr to the temporary buffer we are using for fixed-length data */
diff --git a/src/H5F.c b/src/H5F.c
index ff144c5..922fd45 100644
--- a/src/H5F.c
+++ b/src/H5F.c
@@ -218,7 +218,8 @@ H5Fget_create_plist(hid_t file_id)
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_FCPL, H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
+    if(H5VL_file_get(obj, vol_plugin->cls, H5VL_FILE_GET_FCPL, H5AC_dxpl_id, 
+                     H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file creation properties")
 
 done:
@@ -265,7 +266,7 @@ H5Fget_access_plist(hid_t file_id)
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_file_get(file, vol_plugin, H5VL_FILE_GET_FAPL, H5AC_dxpl_id, 
+    if(H5VL_file_get(file, vol_plugin->cls, H5VL_FILE_GET_FAPL, H5AC_dxpl_id, 
                      H5_REQUEST_NULL, &fapl_id) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file creation properties")
 
@@ -337,7 +338,7 @@ H5Fget_obj_count(hid_t file_id, unsigned types)
         if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(file_id)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-        if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_OBJ_COUNT, H5AC_dxpl_id, 
+        if(H5VL_file_get(obj, vol_plugin->cls, H5VL_FILE_GET_OBJ_COUNT, H5AC_dxpl_id, 
                          H5_REQUEST_NULL, types, &ret_value) < 0)
             HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get object count in file(s)")
     }
@@ -449,7 +450,7 @@ H5Fget_obj_ids(hid_t file_id, unsigned types, size_t max_objs, hid_t *oid_list)
         if(NULL == (obj = (void *)H5I_object_verify(file_id, H5I_FILE)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-        if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_OBJ_IDS, H5AC_dxpl_id, H5_REQUEST_NULL, 
+        if(H5VL_file_get(obj, vol_plugin->cls, H5VL_FILE_GET_OBJ_IDS, H5AC_dxpl_id, H5_REQUEST_NULL, 
                          types, max_objs, oid_list, &ret_value) < 0)
             HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get object count in file(s)")
     }
@@ -525,7 +526,7 @@ H5Fget_vfd_handle(hid_t file_id, hid_t fapl, void **file_handle)
     if(NULL == (obj = (void *)H5I_object(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_optional(obj, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_file_optional(obj, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL, 
                           H5VL_FILE_GET_VFD_HANDLE, file_handle, fapl) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file handle")
 
@@ -607,9 +608,12 @@ done:
 hid_t
 H5Fcreate(const char *filename, unsigned flags, hid_t fcpl_id, hid_t fapl_id)
 {
-    void    *file = NULL;              /*file token from VOL plugin */
-    H5VL_t  *vol_plugin;        /* VOL plugin information */
-    hid_t    ret_value;	        /*return value */
+    void *file = NULL;            /* file token from VOL plugin */
+    H5VL_t *vol_plugin = NULL;    /* VOL plugin information */
+    H5P_genplist_t *plist;        /* Property list pointer */
+    hid_t plugin_id;              /* VOL plugin identigier attached to fapl_id */
+    H5VL_class_t *vol_cls = NULL; /* VOL Class structure for callback info */
+    hid_t ret_value;	          /* return value */
 
     FUNC_ENTER_API(FAIL)
     H5TRACE4("i", "*sIuii", filename, flags, fcpl_id, fapl_id);
@@ -640,13 +644,30 @@ H5Fcreate(const char *filename, unsigned flags, hid_t fcpl_id, hid_t fapl_id)
         if(TRUE != H5P_isa_class(fapl_id, H5P_FILE_ACCESS))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not file access property list")
 
+    /* get the VOL info from the fapl */
+    if(NULL == (plist = (H5P_genplist_t *)H5I_object(fapl_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file access property list")
+    if(H5P_get(plist, H5F_ACS_VOL_ID_NAME, &plugin_id) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get vol plugin ID")
+
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
+
     /* create a new file or truncate an existing file through the VOL */
-    if(NULL == (file = H5VL_file_create(&vol_plugin, filename, flags, fcpl_id, fapl_id, 
+    if(NULL == (file = H5VL_file_create(vol_cls, filename, flags, fcpl_id, fapl_id, 
                                         H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to create file")
 
+    /* Build the vol plugin struct */
+    if(NULL == (vol_plugin = (H5VL_t *)H5MM_calloc(sizeof(H5VL_t))))
+        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
+
+    vol_plugin->cls = vol_cls;
+    vol_plugin->nrefs = 0;
+    vol_plugin->id = plugin_id;
+
     /* Get an atom for the file with the VOL information as the auxilary struct*/
-    if((ret_value = H5I_register2(H5I_FILE, file, vol_plugin, TRUE)) < 0)
+    if((ret_value = H5VL_register_id(H5I_FILE, file, vol_plugin, TRUE)) < 0)
 	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize file handle")
 
 done:
@@ -697,9 +718,12 @@ done:
 hid_t
 H5Fopen(const char *filename, unsigned flags, hid_t fapl_id)
 {
-    void    *file = NULL;              /*file token from VOL plugin */
-    H5VL_t  *vol_plugin;        /* VOL plugin information */
-    hid_t   ret_value;	        /*return value			*/
+    void *file = NULL;            /* file token from VOL plugin */
+    H5VL_t *vol_plugin = NULL;    /* VOL plugin information */
+    H5P_genplist_t *plist;        /* Property list pointer */
+    hid_t plugin_id;              /* VOL plugin identigier attached to fapl_id */
+    H5VL_class_t *vol_cls = NULL; /* VOL Class structure for callback info */
+    hid_t ret_value;	          /* return value */
 
     FUNC_ENTER_API(FAIL)
     H5TRACE3("i", "*sIui", filename, flags, fapl_id);
@@ -717,12 +741,29 @@ H5Fopen(const char *filename, unsigned flags, hid_t fapl_id)
         if(TRUE != H5P_isa_class(fapl_id, H5P_FILE_ACCESS))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not file access property list")
 
+    /* get the VOL info from the fapl */
+    if(NULL == (plist = (H5P_genplist_t *)H5I_object(fapl_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file access property list")
+    if(H5P_get(plist, H5F_ACS_VOL_ID_NAME, &plugin_id) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get vol plugin ID")
+
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
+
     /* Open the file through the VOL layer */
-    if(NULL == (file = H5VL_file_open(&vol_plugin, filename, flags, fapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)))
+    if(NULL == (file = H5VL_file_open(vol_cls, filename, flags, fapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to create file")
 
+    /* Build the vol plugin struct */
+    if(NULL == (vol_plugin = (H5VL_t *)H5MM_calloc(sizeof(H5VL_t))))
+        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
+
+    vol_plugin->cls = vol_cls;
+    vol_plugin->nrefs = 0;
+    vol_plugin->id = plugin_id;
+
     /* Get an atom for the file with the VOL information as the auxilary struct*/
-    if((ret_value = H5I_register2(H5I_FILE, file, vol_plugin, TRUE)) < 0)
+    if((ret_value = H5VL_register_id(H5I_FILE, file, vol_plugin, TRUE)) < 0)
 	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize file handle")
 
 done:
@@ -769,7 +810,7 @@ H5Fflush(hid_t object_id, H5F_scope_t scope)
     if(NULL == (obj = (void *)H5VL_get_object(object_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_specific(obj, vol_plugin, H5VL_FILE_FLUSH, H5AC_dxpl_id, 
+    if(H5VL_file_specific(obj, vol_plugin->cls, H5VL_FILE_FLUSH, H5AC_dxpl_id, 
                           H5_REQUEST_NULL, obj_type, scope) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTFLUSH, FAIL, "unable to flush file")
 
@@ -842,8 +883,13 @@ H5F_close_file(void *file, H5VL_t *vol_plugin)
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Close the file through the VOL*/
-    if((ret_value = H5VL_file_close(file, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_file_close(file, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_FILE, H5E_CANTCLOSEFILE, FAIL, "unable to close file")
+
+    /* decrement ref count on VOL ID */
+    if(H5VL_free_id(vol_plugin) < 0)
+	HGOTO_ERROR(H5E_FILE, H5E_CANTDEC, FAIL, "unable to decrement ref count on VOL plugin")
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5F_close_file() */
@@ -890,19 +936,15 @@ H5Freopen(hid_t file_id)
     if(NULL == (obj = (void *)H5I_object(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_optional(obj, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_file_optional(obj, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL, 
                           H5VL_FILE_REOPEN, &file) < 0)
 	HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to reopen file")
 
     if (NULL == file)
         HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to reopen file")
 
-    vol_plugin->nrefs ++;
-    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINC, FAIL, "unable to increment ref count on VOL plugin")
-
     /* Get an atom for the file with the VOL information as the auxilary struct*/
-    if((ret_value = H5I_register2(H5I_FILE, file, vol_plugin, TRUE)) < 0)
+    if((ret_value = H5VL_register_id(H5I_FILE, file, vol_plugin, TRUE)) < 0)
 	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize file handle")
 
 done:
@@ -944,7 +986,7 @@ H5Fget_intent(hid_t file_id, unsigned *intent_flags)
         if(NULL == (obj = (void *)H5I_object(file_id)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-        if((ret_value = H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_INTENT, 
+        if((ret_value = H5VL_file_get(obj, vol_plugin->cls, H5VL_FILE_GET_INTENT, 
                                       H5AC_dxpl_id, H5_REQUEST_NULL, intent_flags)) < 0)
             HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file intent")
     }
@@ -986,7 +1028,7 @@ H5Fget_freespace(hid_t file_id)
     if(NULL == (obj = (void *)H5I_object(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_optional(obj, vol_plugin, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_file_optional(obj, vol_plugin->cls, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                           H5VL_FILE_GET_FREE_SPACE, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file free space")
 
@@ -1029,7 +1071,7 @@ H5Fget_filesize(hid_t file_id, hsize_t *size)
     if(NULL == (file = (void *)H5I_object_verify(file_id, H5I_FILE)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "not a file ID")
 
-    if(H5VL_file_optional(file, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_file_optional(file, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL, 
                           H5VL_FILE_GET_SIZE, size) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file size")
 
@@ -1098,7 +1140,7 @@ H5Fget_file_image(hid_t file_id, void *buf_ptr, size_t buf_len)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* get image through the VOL */
-    if(H5VL_file_optional(file, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_file_optional(file, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL, 
                           H5VL_FILE_GET_FILE_IMAGE, buf_ptr, &ret_value, buf_len) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file image")
 
@@ -1147,7 +1189,7 @@ H5Fget_mdc_config(hid_t file_id, H5AC_cache_config_t *config_ptr)
     if(NULL == (obj = (void *)H5I_object(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_optional(obj, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_file_optional(obj, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL, 
                           H5VL_FILE_GET_MDC_CONF, config_ptr) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get mdc configuration")
 
@@ -1188,7 +1230,7 @@ H5Fset_mdc_config(hid_t file_id, H5AC_cache_config_t *config_ptr)
     if(NULL == (obj = (void *)H5I_object(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_optional(obj, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_file_optional(obj, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL, 
                           H5VL_FILE_SET_MDC_CONFIG, config_ptr) < 0)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "uanvle to set MDC configuration")
 
@@ -1234,7 +1276,7 @@ H5Fget_mdc_hit_rate(hid_t file_id, double *hit_rate_ptr)
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_file_optional(file, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_file_optional(file, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL, 
                           H5VL_FILE_GET_MDC_HR, hit_rate_ptr) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get MDC hit rate")
 
@@ -1280,7 +1322,7 @@ H5Fget_mdc_size(hid_t file_id, size_t *max_size_ptr, size_t *min_clean_size_ptr,
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_file_optional(file, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL, H5VL_FILE_GET_MDC_SIZE, 
+    if(H5VL_file_optional(file, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL, H5VL_FILE_GET_MDC_SIZE, 
                           max_size_ptr, min_clean_size_ptr, cur_size_ptr, cur_num_entries_ptr) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get MDC size")
 
@@ -1327,7 +1369,7 @@ H5Freset_mdc_hit_rate_stats(hid_t file_id)
     if(NULL == (obj = (void *)H5I_object(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_optional(obj, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_file_optional(obj, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL, 
                           H5VL_FILE_RESET_MDC_HIT_RATE) < 0)
         HGOTO_ERROR(H5E_CACHE, H5E_SYSTEM, FAIL, "can't reset cache hit rate")
 
@@ -1383,7 +1425,7 @@ H5Fget_name(hid_t obj_id, char *name/*out*/, size_t size)
     if(NULL == (obj = (void *)H5VL_get_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_NAME, H5AC_dxpl_id, H5_REQUEST_NULL,
+    if(H5VL_file_get(obj, vol_plugin->cls, H5VL_FILE_GET_NAME, H5AC_dxpl_id, H5_REQUEST_NULL,
                      type, size, name, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file name")
 
@@ -1438,7 +1480,7 @@ H5Fget_info2(hid_t obj_id, H5F_info2_t *finfo)
     if(NULL == (obj = (void *)H5VL_get_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_optional(obj, vol_plugin, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_file_optional(obj, vol_plugin->cls, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                           H5VL_FILE_GET_INFO, type, finfo) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file info")
 done:
@@ -1482,7 +1524,7 @@ H5Fget_free_sections(hid_t file_id, H5F_mem_t type, size_t nsects,
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_file_optional(file, vol_plugin, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_file_optional(file, vol_plugin->cls, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                           H5VL_FILE_GET_FREE_SECTIONS, sect_info, &ret_value, type, nsects) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get file free sections")
 done:
@@ -1522,7 +1564,7 @@ H5Fclear_elink_file_cache(hid_t file_id)
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(file_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_file_optional(file, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_file_optional(file, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL, 
                           H5VL_FILE_CLEAR_ELINK_CACHE) < 0)
         HGOTO_ERROR(H5E_FILE, H5E_CANTRELEASE, FAIL, "can't release external file cache")
 
diff --git a/src/H5Fint.c b/src/H5Fint.c
index 8224d90..96ea58a 100644
--- a/src/H5Fint.c
+++ b/src/H5Fint.c
@@ -280,7 +280,7 @@ H5F_get_obj_count_cb(void UNUSED *obj_ptr, hid_t obj_id, void *key)
     if(NULL == (obj = (void *)H5I_object_verify(obj_id, H5I_FILE)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file id")
 
-    if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_OBJ_COUNT, H5AC_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_file_get(obj, vol_plugin->cls, H5VL_FILE_GET_OBJ_COUNT, H5AC_dxpl_id, H5_REQUEST_NULL, 
                      udata->types, &obj_count) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, H5_ITER_ERROR, "unable to get object count in file(s)")
 
@@ -355,7 +355,7 @@ H5F_get_obj_ids_cb(void UNUSED *obj_ptr, hid_t obj_id, void *key)
     if(NULL == (obj = (void *)H5I_object_verify(obj_id, H5I_FILE)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_get(obj, vol_plugin, H5VL_FILE_GET_OBJ_IDS, H5AC_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_file_get(obj, vol_plugin->cls, H5VL_FILE_GET_OBJ_IDS, H5AC_dxpl_id, H5_REQUEST_NULL, 
                      udata->types, udata->max_objs, udata->oid_list, &obj_count) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, H5_ITER_ERROR, "unable to get object count in file(s)")
 
diff --git a/src/H5Fmount.c b/src/H5Fmount.c
index 500852d..b9fc596 100644
--- a/src/H5Fmount.c
+++ b/src/H5Fmount.c
@@ -509,7 +509,7 @@ H5Fmount(hid_t loc_id, const char *name, hid_t child_id, hid_t plist_id)
     if(NULL == (file = (void *)H5I_object(child_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_specific(obj, vol_plugin1, H5VL_FILE_MOUNT, H5AC_dxpl_id, 
+    if(H5VL_file_specific(obj, vol_plugin1->cls, H5VL_FILE_MOUNT, H5AC_dxpl_id, 
                           H5_REQUEST_NULL, type, name, file, plist_id) < 0)
 	HGOTO_ERROR(H5E_FILE, H5E_MOUNT, FAIL, "unable to mount file")
 
@@ -565,7 +565,7 @@ H5Funmount(hid_t loc_id, const char *name)
     if(NULL == (obj = (void *)H5I_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
-    if(H5VL_file_specific(obj, vol_plugin, H5VL_FILE_UNMOUNT, H5AC_dxpl_id, 
+    if(H5VL_file_specific(obj, vol_plugin->cls, H5VL_FILE_UNMOUNT, H5AC_dxpl_id, 
                           H5_REQUEST_NULL, type, name) < 0)
 	HGOTO_ERROR(H5E_FILE, H5E_MOUNT, FAIL, "unable to unmount file")
 
diff --git a/src/H5G.c b/src/H5G.c
index f182881..7d2bcb4 100644
--- a/src/H5G.c
+++ b/src/H5G.c
@@ -329,17 +329,17 @@ H5Gcreate2(hid_t loc_id, const char *name, hid_t lcpl_id, hid_t gcpl_id, hid_t g
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the group through the VOL */
-    if(NULL == (grp = H5VL_group_create(obj, loc_params, vol_plugin, name, gcpl_id, gapl_id, 
+    if(NULL == (grp = H5VL_group_create(obj, loc_params, vol_plugin->cls, name, gcpl_id, gapl_id, 
                                         H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create group")
 
-    /* Get an atom for the group */
-    if((ret_value = H5I_register2(H5I_GROUP, grp, vol_plugin, TRUE)) < 0)
-	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize dataset handle")
+    /* Get an atom for the group with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_GROUP, grp, vol_plugin, TRUE)) < 0)
+	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize group handle")
 
 done:
     if (ret_value < 0 && grp)
-        if(H5VL_group_close (grp, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_group_close (grp, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to release group")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Gcreate2() */
@@ -418,17 +418,17 @@ H5Gcreate_anon(hid_t loc_id, hid_t gcpl_id, hid_t gapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the group through the VOL */
-    if(NULL == (grp = H5VL_group_create(obj, loc_params, vol_plugin, NULL, gcpl_id, gapl_id, 
+    if(NULL == (grp = H5VL_group_create(obj, loc_params, vol_plugin->cls, NULL, gcpl_id, gapl_id, 
                                         H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create group")
 
-    /* Get an atom for the group */
-    if((ret_value = H5I_register2(H5I_GROUP, grp, vol_plugin, TRUE)) < 0)
-	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize dataset handle")
+    /* Get an atom for the group with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_GROUP, grp, vol_plugin, TRUE)) < 0)
+	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize group handle")
 
 done:
     if (ret_value < 0 && grp)
-        if(H5VL_group_close (grp, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_group_close (grp, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to release group")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Gcreate_anon() */
@@ -486,17 +486,17 @@ H5Gopen2(hid_t loc_id, const char *name, hid_t gapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the group through the VOL */
-    if(NULL == (grp = H5VL_group_open(obj, loc_params, vol_plugin, name, gapl_id, 
+    if(NULL == (grp = H5VL_group_open(obj, loc_params, vol_plugin->cls, name, gapl_id, 
                                       H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open group")
 
-    /* Get an atom for the group */
-    if((ret_value = H5I_register2(H5I_GROUP, grp, vol_plugin, TRUE)) < 0)
-	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize dataset handle")
+    /* Get an atom for the group with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_GROUP, grp, vol_plugin, TRUE)) < 0)
+	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize group handle")
 
 done:
     if (ret_value < 0 && grp)
-        if(H5VL_group_close (grp, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_group_close (grp, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to release group")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Gopen2() */
@@ -536,7 +536,7 @@ H5Gget_create_plist(hid_t grp_id)
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(grp_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_group_get(grp, vol_plugin, H5VL_GROUP_GET_GCPL, H5AC_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_group_get(grp, vol_plugin->cls, H5VL_GROUP_GET_GCPL, H5AC_dxpl_id, H5_REQUEST_NULL, 
                       &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group creation properties")
 
@@ -588,7 +588,7 @@ H5Gget_info(hid_t loc_id, H5G_info_t *grp_info)
     loc_params.obj_type = id_type;
 
     /* Get the group info through the VOL using the location token */
-    if((ret_value = H5VL_group_get(obj, vol_plugin, H5VL_GROUP_GET_INFO, H5AC_ind_dxpl_id, 
+    if((ret_value = H5VL_group_get(obj, vol_plugin->cls, H5VL_GROUP_GET_INFO, H5AC_ind_dxpl_id, 
                                    H5_REQUEST_NULL, loc_params, grp_info)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
@@ -646,7 +646,7 @@ H5Gget_info_by_name(hid_t loc_id, const char *name, H5G_info_t *grp_info,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid group identifier")
 
     /* Get the group info through the VOL using the location token */
-    if((ret_value = H5VL_group_get(obj, vol_plugin, H5VL_GROUP_GET_INFO, H5AC_ind_dxpl_id, 
+    if((ret_value = H5VL_group_get(obj, vol_plugin->cls, H5VL_GROUP_GET_INFO, H5AC_ind_dxpl_id, 
                                    H5_REQUEST_NULL, loc_params, grp_info)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
@@ -713,7 +713,7 @@ H5Gget_info_by_idx(hid_t loc_id, const char *group_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid group identifier")
 
     /* Get the group info through the VOL using the location token */
-    if((ret_value = H5VL_group_get(obj, vol_plugin, H5VL_GROUP_GET_INFO, H5AC_ind_dxpl_id, 
+    if((ret_value = H5VL_group_get(obj, vol_plugin->cls, H5VL_GROUP_GET_INFO, H5AC_ind_dxpl_id, 
                                    H5_REQUEST_NULL, loc_params, grp_info)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
@@ -786,9 +786,13 @@ H5G_close_group(void *grp, H5VL_t *vol_plugin)
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Close the group through the VOL*/
-    if((ret_value = H5VL_group_close(grp, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
+    if((ret_value = H5VL_group_close(grp, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to close group")
 
+    /* decrement ref count on VOL ID */
+    if(H5VL_free_id(vol_plugin) < 0)
+	HGOTO_ERROR(H5E_SYM, H5E_CANTDEC, FAIL, "unable to decrement ref count on VOL plugin")
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5G_close_group() */
diff --git a/src/H5Gdeprec.c b/src/H5Gdeprec.c
index f1451a9..22e09ed 100644
--- a/src/H5Gdeprec.c
+++ b/src/H5Gdeprec.c
@@ -286,20 +286,20 @@ H5Gcreate1(hid_t loc_id, const char *name, size_t size_hint)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the group through the VOL */
-    if(NULL == (grp = H5VL_group_create(obj, loc_params, vol_plugin, name, tmp_gcpl, 
+    if(NULL == (grp = H5VL_group_create(obj, loc_params, vol_plugin->cls, name, tmp_gcpl, 
                                         H5P_GROUP_ACCESS_DEFAULT, H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create group")
 
-    /* Get an atom for the group */
-    if((ret_value = H5I_register2(H5I_GROUP, grp, vol_plugin, TRUE)) < 0)
-	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize dataset handle")
+    /* Get an atom for the group with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_GROUP, grp, vol_plugin, TRUE)) < 0)
+	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize group handle")
 
 done:
     if(tmp_gcpl > 0 && tmp_gcpl != H5P_GROUP_CREATE_DEFAULT)
         if(H5I_dec_ref(tmp_gcpl) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to release property list")
     if (ret_value < 0 && grp)
-        if(H5VL_group_close (grp, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_group_close (grp, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to release group")
 
     FUNC_LEAVE_API(ret_value)
@@ -351,17 +351,17 @@ H5Gopen1(hid_t loc_id, const char *name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the group through the VOL */
-    if(NULL == (grp = H5VL_group_open(obj, loc_params, vol_plugin, name, H5P_DEFAULT, 
+    if(NULL == (grp = H5VL_group_open(obj, loc_params, vol_plugin->cls, name, H5P_DEFAULT, 
                                       H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create group")
 
-    /* Get an atom for the group */
-    if((ret_value = H5I_register2(H5I_GROUP, grp, vol_plugin, TRUE)) < 0)
-	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize dataset handle")
+    /* Get an atom for the group with the VOL information as the auxilary struct*/
+    if((ret_value = H5VL_register_id(H5I_GROUP, grp, vol_plugin, TRUE)) < 0)
+	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize group handle")
 
 done:
     if (ret_value < 0 && grp)
-        if(H5VL_group_close (grp, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_group_close (grp, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to release group")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Gopen1() */
@@ -424,7 +424,7 @@ H5Glink(hid_t cur_loc_id, H5G_link_t type, const char *cur_name, const char *new
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't set property value for target loc params")
 
         /* Create the link through the VOL */
-        if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_HARD, NULL, loc_params2, vol_plugin,
+        if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_HARD, NULL, loc_params2, vol_plugin->cls,
                                          lcpl_id, H5P_DEFAULT, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
     } /* end if */
@@ -450,7 +450,7 @@ H5Glink(hid_t cur_loc_id, H5G_link_t type, const char *cur_name, const char *new
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get property value for target name")
 
         /* Create the link through the VOL */
-        if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_SOFT, obj, loc_params, vol_plugin, 
+        if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_SOFT, obj, loc_params, vol_plugin->cls, 
                                          lcpl_id, H5P_DEFAULT, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
     } /* end else if */
@@ -531,7 +531,7 @@ H5Glink2(hid_t cur_loc_id, const char *cur_name, H5G_link_t type,
 
         /* Create the link through the VOL */
         if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_HARD, obj2, loc_params2, 
-                                         (vol_plugin1!=NULL ? vol_plugin1 : vol_plugin2),
+                                         (vol_plugin1!=NULL ? vol_plugin1->cls : vol_plugin2->cls),
                                          lcpl_id, H5P_DEFAULT, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
     } /* end if */
@@ -562,7 +562,7 @@ H5Glink2(hid_t cur_loc_id, const char *cur_name, H5G_link_t type,
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get property value for target name")
 
         /* Create the link through the VOL */
-        if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_SOFT, obj, loc_params, vol_plugin, 
+        if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_SOFT, obj, loc_params, vol_plugin->cls, 
                                          lcpl_id, H5P_DEFAULT, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
             HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
     } /* end else if */
@@ -610,7 +610,7 @@ H5Gmove(hid_t src_loc_id, const char *src_name, const char *dst_name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the link through the VOL */
-    if((ret_value = H5VL_link_move(obj, loc_params1, NULL, loc_params2, vol_plugin,
+    if((ret_value = H5VL_link_move(obj, loc_params1, NULL, loc_params2, vol_plugin->cls,
                                    H5P_DEFAULT, H5P_DEFAULT, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
@@ -676,7 +676,7 @@ H5Gmove2(hid_t src_loc_id, const char *src_name, hid_t dst_loc_id,
 
     /* Move the link through the VOL */
     if((ret_value = H5VL_link_move(obj1, loc_params1, obj2, loc_params2, 
-                                   (vol_plugin1!=NULL ? vol_plugin1 : vol_plugin2), 
+                                   (vol_plugin1!=NULL ? vol_plugin1->cls : vol_plugin2->cls), 
                                    H5P_DEFAULT, H5P_DEFAULT, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
@@ -719,7 +719,7 @@ H5Gunlink(hid_t loc_id, const char *name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Delete the link through the VOL */
-    if(H5VL_link_specific(obj, loc_params, vol_plugin, H5VL_LINK_DELETE, 
+    if(H5VL_link_specific(obj, loc_params, vol_plugin->cls, H5VL_LINK_DELETE, 
                           H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTDELETE, FAIL, "unable to delete link")
 
@@ -764,7 +764,7 @@ H5Gget_linkval(hid_t loc_id, const char *name, size_t size, char *buf/*out*/)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Get the link info through the VOL */
-    if((ret_value = H5VL_link_get(obj, loc_params, vol_plugin, H5VL_LINK_GET_VAL, 
+    if((ret_value = H5VL_link_get(obj, loc_params, vol_plugin->cls, H5VL_LINK_GET_VAL, 
                                   H5AC_ind_dxpl_id, H5_REQUEST_NULL, buf, size)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get link value")
 
@@ -904,7 +904,7 @@ H5Gset_comment(hid_t loc_id, const char *name, const char *comment)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* set comment on object through the VOL */
-    if(H5VL_object_optional(obj, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_object_optional(obj, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL, 
                             H5VL_OBJECT_SET_COMMENT, loc_params, comment) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to set comment value")
 
@@ -965,7 +965,7 @@ H5Gget_comment(hid_t loc_id, const char *name, size_t bufsize, char *buf)
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_object_optional(obj, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_object_optional(obj, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL, 
                             H5VL_OBJECT_GET_COMMENT, loc_params, buf, bufsize, &size) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get object comment")
 
diff --git a/src/H5I.c b/src/H5I.c
index 4839624..314adf2 100644
--- a/src/H5I.c
+++ b/src/H5I.c
@@ -2282,20 +2282,17 @@ H5Iget_file_id(hid_t obj_id)
         }
 
         /* Get the file through the VOL */
-        if(H5VL_file_get(obj, vol_plugin, H5VL_OBJECT_GET_FILE, H5AC_dxpl_id, H5_REQUEST_NULL, type, &file) < 0)
+        if(H5VL_file_get(obj, vol_plugin->cls, H5VL_OBJECT_GET_FILE, H5AC_dxpl_id, 
+                         H5_REQUEST_NULL, type, &file) < 0)
             HGOTO_ERROR(H5E_INTERNAL, H5E_CANTINIT, FAIL, "unable to get file")
         if (NULL == file)
             HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to reopen file")
 
         /* Check if the ID already exists and procceed accordingly */
         if (FAIL == (ret_value = H5I_get_id(file, H5I_FILE))) {
-            /* resurrect the ID */
-            if((ret_value = H5I_register2(H5I_FILE, file, vol_plugin, TRUE)) < 0)
-                HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to register group")
-            /* increment the ref count on the VOL plugin for the new ID */
-            vol_plugin->nrefs ++;
-            if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
-                HGOTO_ERROR(H5E_FILE, H5E_CANTINC, FAIL, "unable to increment ref count on VOL plugin")
+            /* Get an atom for the file with the VOL information as the auxilary struct*/
+            if((ret_value = H5VL_register_id(H5I_FILE, file, vol_plugin, TRUE)) < 0)
+                HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize file handle")
         }
         else {
             /* Increment ref count on existing ID */
@@ -2478,7 +2475,7 @@ H5I__get_id_cb(void *_item, void UNUSED *_key, void *_udata)
 /*-------------------------------------------------------------------------
  * Function:	H5I_get_id
  *
- * Purpose:     return ID of vol object
+ * Purpose:     return ID of object
  *
  * Return:	Success:	id of object
  *		Failure:	FAIL
diff --git a/src/H5L.c b/src/H5L.c
index fe7b39c..7ce316a 100644
--- a/src/H5L.c
+++ b/src/H5L.c
@@ -328,7 +328,7 @@ H5Lmove(hid_t src_loc_id, const char *src_name, hid_t dst_loc_id,
 
     /* Move the link through the VOL */
     if(H5VL_link_move(obj1, loc_params1, obj2, loc_params2, 
-                      (vol_plugin1!=NULL ? vol_plugin1 : vol_plugin2), 
+                      (vol_plugin1!=NULL ? vol_plugin1->cls : vol_plugin2->cls), 
                       lcpl_id, lapl_id, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
@@ -419,7 +419,7 @@ H5Lcopy(hid_t src_loc_id, const char *src_name, hid_t dst_loc_id,
 
     /* Move the link through the VOL */
     if(H5VL_link_copy(obj1, loc_params1, obj2, loc_params2, 
-                      (vol_plugin1!=NULL ? vol_plugin1 : vol_plugin2), 
+                      (vol_plugin1!=NULL ? vol_plugin1->cls : vol_plugin2->cls), 
                       lcpl_id, lapl_id, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 done:
@@ -496,7 +496,7 @@ H5Lcreate_soft(const char *link_target,
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get property value for target name")
 
     /* Create the link through the VOL */
-    if(H5VL_link_create(H5VL_LINK_CREATE_SOFT, obj, loc_params, vol_plugin,
+    if(H5VL_link_create(H5VL_LINK_CREATE_SOFT, obj, loc_params, vol_plugin->cls,
                         lcpl_id, lapl_id, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
@@ -599,7 +599,7 @@ H5Lcreate_hard(hid_t cur_loc_id, const char *cur_name,
 
     /* Create the link through the VOL */
     if(H5VL_link_create(H5VL_LINK_CREATE_HARD, obj2, loc_params2, 
-                        (vol_plugin1!=NULL ? vol_plugin1 : vol_plugin2),
+                        (vol_plugin1!=NULL ? vol_plugin1->cls : vol_plugin2->cls),
                         lcpl_id, lapl_id, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
@@ -684,7 +684,7 @@ H5Lcreate_ud(hid_t link_loc_id, const char *link_name, H5L_type_t link_type,
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get property value from plist")
 
     /* Create the link through the VOL */
-    if(H5VL_link_create(H5VL_LINK_CREATE_UD, obj, loc_params, vol_plugin,
+    if(H5VL_link_create(H5VL_LINK_CREATE_UD, obj, loc_params, vol_plugin->cls,
                         lcpl_id, lapl_id, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
@@ -738,7 +738,7 @@ H5Ldelete(hid_t loc_id, const char *name, hid_t lapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Delete the link through the VOL */
-    if(H5VL_link_specific(obj, loc_params, vol_plugin, H5VL_LINK_DELETE, 
+    if(H5VL_link_specific(obj, loc_params, vol_plugin->cls, H5VL_LINK_DELETE, 
                           H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTDELETE, FAIL, "unable to delete link")
 
@@ -807,7 +807,7 @@ H5Ldelete_by_idx(hid_t loc_id, const char *group_name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Delete the link through the VOL */
-    if(H5VL_link_specific(obj, loc_params, vol_plugin, H5VL_LINK_DELETE, 
+    if(H5VL_link_specific(obj, loc_params, vol_plugin->cls, H5VL_LINK_DELETE, 
                           H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTDELETE, FAIL, "unable to delete link")
 
@@ -869,7 +869,7 @@ H5Lget_val(hid_t loc_id, const char *name, void *buf/*out*/, size_t size,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Get the link info through the VOL */
-    if(H5VL_link_get(obj, loc_params, vol_plugin, H5VL_LINK_GET_VAL, 
+    if(H5VL_link_get(obj, loc_params, vol_plugin->cls, H5VL_LINK_GET_VAL, 
                      H5AC_ind_dxpl_id, H5_REQUEST_NULL, buf, size) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get link value")
 
@@ -939,7 +939,7 @@ H5Lget_val_by_idx(hid_t loc_id, const char *group_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Get the link info through the VOL */
-    if(H5VL_link_get(obj, loc_params, vol_plugin, H5VL_LINK_GET_VAL, 
+    if(H5VL_link_get(obj, loc_params, vol_plugin->cls, H5VL_LINK_GET_VAL, 
                      H5AC_ind_dxpl_id, H5_REQUEST_NULL, buf, size) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get link value")
 
@@ -994,7 +994,7 @@ H5Lexists(hid_t loc_id, const char *name, hid_t lapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* check link existence through the VOL */
-    if(H5VL_link_specific(obj, loc_params, vol_plugin, H5VL_LINK_EXISTS,
+    if(H5VL_link_specific(obj, loc_params, vol_plugin->cls, H5VL_LINK_EXISTS,
                           H5AC_ind_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get link info")
 
@@ -1050,7 +1050,7 @@ H5Lget_info(hid_t loc_id, const char *name, H5L_info_t *linfo /*out*/,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Get the link info through the VOL */
-    if(H5VL_link_get(obj, loc_params, vol_plugin, H5VL_LINK_GET_INFO, 
+    if(H5VL_link_get(obj, loc_params, vol_plugin->cls, H5VL_LINK_GET_INFO, 
                      H5AC_ind_dxpl_id, H5_REQUEST_NULL, linfo) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get link info")
 
@@ -1116,7 +1116,7 @@ H5Lget_info_by_idx(hid_t loc_id, const char *group_name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Get the link info through the VOL */
-    if(H5VL_link_get(obj, loc_params, vol_plugin, H5VL_LINK_GET_INFO,
+    if(H5VL_link_get(obj, loc_params, vol_plugin->cls, H5VL_LINK_GET_INFO,
                      H5AC_ind_dxpl_id, H5_REQUEST_NULL, linfo) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get link info")
 
@@ -1312,7 +1312,7 @@ H5Lget_name_by_idx(hid_t loc_id, const char *group_name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Get the link info through the VOL */
-    if(H5VL_link_get(obj, loc_params, vol_plugin, H5VL_LINK_GET_NAME, 
+    if(H5VL_link_get(obj, loc_params, vol_plugin->cls, H5VL_LINK_GET_NAME, 
                      H5AC_ind_dxpl_id, H5_REQUEST_NULL, name, size, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get link name")
 
@@ -1378,7 +1378,7 @@ H5Literate(hid_t id, H5_index_t idx_type, H5_iter_order_t order,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* iterate over the links through the VOL */
-    if((ret_value = H5VL_link_specific(obj, loc_params, vol_plugin, H5VL_LINK_ITER,
+    if((ret_value = H5VL_link_specific(obj, loc_params, vol_plugin->cls, H5VL_LINK_ITER,
                                        H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                                        FALSE, idx_type, order, idx_p, op, op_data)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_BADITER, FAIL, "link iteration failed")
@@ -1452,7 +1452,7 @@ H5Literate_by_name(hid_t loc_id, const char *group_name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* iterate over the links through the VOL */
-    if((ret_value = H5VL_link_specific(obj, loc_params, vol_plugin, H5VL_LINK_ITER,
+    if((ret_value = H5VL_link_specific(obj, loc_params, vol_plugin->cls, H5VL_LINK_ITER,
                                        H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                                        FALSE, idx_type, order, idx_p, op, op_data)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_BADITER, FAIL, "link iteration failed")
@@ -1526,7 +1526,7 @@ H5Lvisit(hid_t grp_id, H5_index_t idx_type, H5_iter_order_t order,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* iterate over the links through the VOL */
-    if((ret_value = H5VL_link_specific(obj, loc_params, vol_plugin, H5VL_LINK_ITER,
+    if((ret_value = H5VL_link_specific(obj, loc_params, vol_plugin->cls, H5VL_LINK_ITER,
                                        H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                                        TRUE, idx_type, order, NULL, op, op_data)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_BADITER, FAIL, "link visit failed")
@@ -1605,7 +1605,7 @@ H5Lvisit_by_name(hid_t loc_id, const char *group_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* visit the links through the VOL */
-    if((ret_value = H5VL_link_specific(obj, loc_params, vol_plugin, H5VL_LINK_ITER,
+    if((ret_value = H5VL_link_specific(obj, loc_params, vol_plugin->cls, H5VL_LINK_ITER,
                                        H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                                        TRUE, idx_type, order, NULL, op, op_data)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_BADITER, FAIL, "link visit failed")
diff --git a/src/H5Lexternal.c b/src/H5Lexternal.c
index 1947d58..a78b0b0 100644
--- a/src/H5Lexternal.c
+++ b/src/H5Lexternal.c
@@ -633,7 +633,7 @@ H5Lcreate_external(const char *file_name, const char *obj_name,
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get property value from plist")
 
     /* Create the link through the VOL */
-    if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_UD, obj, loc_params, vol_plugin,
+    if((ret_value = H5VL_link_create(H5VL_LINK_CREATE_UD, obj, loc_params, vol_plugin->cls,
                                      lcpl_id, lapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
diff --git a/src/H5O.c b/src/H5O.c
index 147b682..00103c4 100644
--- a/src/H5O.c
+++ b/src/H5O.c
@@ -253,7 +253,7 @@ H5Oopen(hid_t loc_id, const char *name, hid_t lapl_id)
     loc_params.obj_type = H5I_get_type(loc_id);
 
     /* Open the object through the VOL */
-    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin, &opened_type, 
+    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin->cls, &opened_type, 
                                               H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open object")
 
@@ -330,7 +330,7 @@ H5Oopen_by_idx(hid_t loc_id, const char *group_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Open the object through the VOL */
-    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin, &opened_type, 
+    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin->cls, &opened_type, 
                                               H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open object")
 
@@ -402,7 +402,7 @@ H5Oopen_by_addr(hid_t loc_id, haddr_t addr)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Open the object through the VOL */
-    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin, &opened_type, 
+    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin->cls, &opened_type, 
                                               H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open object")
 
@@ -510,7 +510,7 @@ H5Olink(hid_t obj_id, hid_t new_loc_id, const char *new_name, hid_t lcpl_id,
 
     /* Create the link through the VOL */
     if(H5VL_link_create(H5VL_LINK_CREATE_HARD, obj2, loc_params2, 
-                        (vol_plugin1!=NULL ? vol_plugin1 : vol_plugin2),
+                        (vol_plugin1!=NULL ? vol_plugin1->cls : vol_plugin2->cls),
                         lcpl_id, lapl_id, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to create link")
 
@@ -561,7 +561,7 @@ H5Oincr_refcount(hid_t object_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* change the ref count through the VOL */
-    if(H5VL_object_specific(obj, loc_params, vol_plugin, H5VL_OBJECT_CHANGE_REF_COUNT, 
+    if(H5VL_object_specific(obj, loc_params, vol_plugin->cls, H5VL_OBJECT_CHANGE_REF_COUNT, 
                             H5AC_dxpl_id, H5_REQUEST_NULL, 1) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_LINKCOUNT, FAIL, "modifying object link count failed")
 
@@ -612,7 +612,7 @@ H5Odecr_refcount(hid_t object_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* change the ref count through the VOL */
-    if(H5VL_object_specific(obj, loc_params, vol_plugin, H5VL_OBJECT_CHANGE_REF_COUNT, 
+    if(H5VL_object_specific(obj, loc_params, vol_plugin->cls, H5VL_OBJECT_CHANGE_REF_COUNT, 
                             H5AC_dxpl_id, H5_REQUEST_NULL, -1) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_LINKCOUNT, FAIL, "modifying object link count failed")
 
@@ -667,7 +667,7 @@ H5Oexists_by_name(hid_t loc_id, const char *name, hid_t lapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* change the ref count through the VOL */
-    if(H5VL_object_specific(obj, loc_params, vol_plugin, H5VL_OBJECT_EXISTS, 
+    if(H5VL_object_specific(obj, loc_params, vol_plugin->cls, H5VL_OBJECT_EXISTS, 
                             H5AC_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, FAIL, "unable to determine if '%s' exists", name)
 
@@ -715,7 +715,7 @@ H5Oget_info(hid_t loc_id, H5O_info_t *oinfo)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Get the group info through the VOL using the location token */
-    if(H5VL_object_optional(obj, vol_plugin, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_object_optional(obj, vol_plugin->cls, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                             H5VL_OBJECT_GET_INFO, loc_params, oinfo) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
@@ -773,7 +773,7 @@ H5Oget_info_by_name(hid_t loc_id, const char *name, H5O_info_t *oinfo, hid_t lap
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Get the group info through the VOL using the location token */
-    if(H5VL_object_optional(obj, vol_plugin, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_object_optional(obj, vol_plugin->cls, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                             H5VL_OBJECT_GET_INFO, loc_params, oinfo) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
@@ -840,7 +840,7 @@ H5Oget_info_by_idx(hid_t loc_id, const char *group_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Get the group info through the VOL using the location token */
-    if(H5VL_object_optional(obj, vol_plugin, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_object_optional(obj, vol_plugin->cls, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                             H5VL_OBJECT_GET_INFO, loc_params, oinfo) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
@@ -888,7 +888,7 @@ H5Oset_comment(hid_t obj_id, const char *comment)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* set comment on object through the VOL */
-    if(H5VL_object_optional(obj, vol_plugin, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_object_optional(obj, vol_plugin->cls, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                             H5VL_OBJECT_SET_COMMENT, loc_params, comment) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to set comment value")
 
@@ -948,7 +948,7 @@ H5Oset_comment_by_name(hid_t loc_id, const char *name, const char *comment,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* set comment on object through the VOL */
-    if(H5VL_object_optional(obj, vol_plugin, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_object_optional(obj, vol_plugin->cls, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                             H5VL_OBJECT_SET_COMMENT, loc_params, comment) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to set comment value")
 
@@ -994,7 +994,7 @@ H5Oget_comment(hid_t loc_id, char *comment, size_t bufsize)
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_object_optional(obj, vol_plugin, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_object_optional(obj, vol_plugin->cls, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                             H5VL_OBJECT_GET_COMMENT, loc_params, comment, bufsize, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get object comment")
 
@@ -1052,7 +1052,7 @@ H5Oget_comment_by_name(hid_t loc_id, const char *name, char *comment, size_t buf
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(H5VL_object_optional(obj, vol_plugin, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_object_optional(obj, vol_plugin->cls, H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                             H5VL_OBJECT_GET_COMMENT, loc_params, comment, bufsize, &ret_value) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get object info")
 
@@ -1124,7 +1124,7 @@ H5Ovisit(hid_t obj_id, H5_index_t idx_type, H5_iter_order_t order,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* iterate over the objects through the VOL */
-    if((ret_value = H5VL_object_specific(obj, loc_params, vol_plugin, H5VL_OBJECT_VISIT,
+    if((ret_value = H5VL_object_specific(obj, loc_params, vol_plugin->cls, H5VL_OBJECT_VISIT,
                                          H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                                          idx_type, order, op, op_data)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_BADITER, FAIL, "link iteration failed")
@@ -1207,7 +1207,7 @@ H5Ovisit_by_name(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* iterate over the objects through the VOL */
-    if((ret_value = H5VL_object_specific(obj, loc_params, vol_plugin, H5VL_OBJECT_VISIT,
+    if((ret_value = H5VL_object_specific(obj, loc_params, vol_plugin->cls, H5VL_OBJECT_VISIT,
                                          H5AC_ind_dxpl_id, H5_REQUEST_NULL, 
                                          idx_type, order, op, op_data)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_BADITER, FAIL, "link iteration failed")
diff --git a/src/H5Ocopy.c b/src/H5Ocopy.c
index f408d80..7ba1c07 100644
--- a/src/H5Ocopy.c
+++ b/src/H5Ocopy.c
@@ -252,8 +252,8 @@ H5Ocopy(hid_t src_loc_id, const char *src_name, hid_t dst_loc_id,
     loc_params2.obj_type = H5I_get_type(dst_loc_id);
 
     /* Open the object through the VOL */
-    if((ret_value = H5VL_object_copy(obj1, loc_params1, vol_plugin1, src_name, 
-                                     obj2, loc_params2, vol_plugin2, dst_name, 
+    if((ret_value = H5VL_object_copy(obj1, loc_params1, vol_plugin1->cls, src_name, 
+                                     obj2, loc_params2, vol_plugin2->cls, dst_name, 
                                      ocpypl_id, lcpl_id, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to copy object")
 
diff --git a/src/H5R.c b/src/H5R.c
index f813f93..4adea98 100644
--- a/src/H5R.c
+++ b/src/H5R.c
@@ -381,7 +381,7 @@ H5Rcreate(void *ref, hid_t loc_id, const char *name, H5R_type_t ref_type, hid_t
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* create the ref through the VOL */
-    if(ret_value = H5VL_object_specific(obj, loc_params, vol_plugin, H5VL_REF_CREATE, 
+    if(ret_value = H5VL_object_specific(obj, loc_params, vol_plugin->cls, H5VL_REF_CREATE, 
                                         H5AC_dxpl_id, H5_REQUEST_NULL, 
                                         ref, name, ref_type, space_id) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_LINKCOUNT, FAIL, "modifying object link count failed")
@@ -610,7 +610,7 @@ H5Rdereference2(hid_t obj_id, hid_t oapl_id, H5R_type_t ref_type, const void *_r
     loc_params.obj_type = H5I_get_type(obj_id);
 
     /* Open the object through the VOL */
-    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin, &opened_type, 
+    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin->cls, &opened_type, 
                                               H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_REFERENCE, H5E_CANTINIT, FAIL, "unable to dereference object")
 
@@ -743,7 +743,7 @@ H5Rget_region(hid_t id, H5R_type_t ref_type, const void *ref)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Get the space id through the VOL */
-    if(H5VL_object_get(obj, loc_params, vol_plugin, H5VL_REF_GET_REGION, 
+    if(H5VL_object_get(obj, loc_params, vol_plugin->cls, H5VL_REF_GET_REGION, 
                        H5AC_ind_dxpl_id, H5_REQUEST_NULL, &ret_value, ref_type, ref) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
@@ -890,7 +890,7 @@ H5Rget_obj_type2(hid_t id, H5R_type_t ref_type, const void *ref,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* get the object type through the VOL */
-    if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, H5VL_REF_GET_TYPE, 
+    if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin->cls, H5VL_REF_GET_TYPE, 
                                     H5AC_ind_dxpl_id, H5_REQUEST_NULL, obj_type, ref_type, ref)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
@@ -1065,7 +1065,7 @@ H5Rget_name(hid_t id, H5R_type_t ref_type, const void *_ref, char *name,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* get the object type through the VOL */
-    if(H5VL_object_get(obj, loc_params, vol_plugin, H5VL_REF_GET_NAME, H5AC_dxpl_id, H5_REQUEST_NULL, 
+    if(H5VL_object_get(obj, loc_params, vol_plugin->cls, H5VL_REF_GET_NAME, H5AC_dxpl_id, H5_REQUEST_NULL, 
                        &ret_value, name, size, ref_type, _ref) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 done:
diff --git a/src/H5Rdeprec.c b/src/H5Rdeprec.c
index 1581168..1f95827 100644
--- a/src/H5Rdeprec.c
+++ b/src/H5Rdeprec.c
@@ -185,7 +185,7 @@ H5Rget_obj_type1(hid_t id, H5R_type_t ref_type, const void *ref)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* get the object type through the VOL */
-    if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin, H5VL_REF_GET_TYPE,
+    if((ret_value = H5VL_object_get(obj, loc_params, vol_plugin->cls, H5VL_REF_GET_TYPE,
                                     H5AC_ind_dxpl_id, H5_REQUEST_NULL, &obj_type, ref_type, ref)) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get group info")
 
@@ -252,7 +252,7 @@ H5Rdereference1(hid_t obj_id, H5R_type_t ref_type, const void *_ref)
     loc_params.obj_type = H5I_get_type(obj_id);
 
     /* Open the object through the VOL */
-    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin, &opened_type, 
+    if(NULL == (opened_obj = H5VL_object_open(obj, loc_params, vol_plugin->cls, &opened_type, 
                                               H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open object")
 
diff --git a/src/H5Tcommit.c b/src/H5Tcommit.c
index efc443d..ed4d37b 100644
--- a/src/H5Tcommit.c
+++ b/src/H5Tcommit.c
@@ -173,7 +173,7 @@ H5Tcommit2(hid_t loc_id, const char *name, hid_t type_id, hid_t lcpl_id,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* commit the datatype through the VOL */
-    if (NULL == (dt = H5VL_datatype_commit(obj, loc_params, vol_plugin, name, type_id, lcpl_id, 
+    if (NULL == (dt = H5VL_datatype_commit(obj, loc_params, vol_plugin->cls, name, type_id, lcpl_id, 
                                            tcpl_id, tapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to commit datatype")
 
@@ -186,6 +186,10 @@ H5Tcommit2(hid_t loc_id, const char *name, hid_t type_id, hid_t lcpl_id,
     if (H5I_register_aux(type_id, vol_plugin) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "can't attach vol info to ID")
 
+    vol_plugin->nrefs ++;
+    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTINC, FAIL, "unable to increment ref count on VOL plugin")
+
 done:
     FUNC_LEAVE_API(ret_value)
 } /* end H5Tcommit2() */
@@ -336,7 +340,7 @@ H5Tcommit_anon(hid_t loc_id, hid_t type_id, hid_t tcpl_id, hid_t tapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* commite the datatype through the VOL */
-    if (NULL == (dt = H5VL_datatype_commit(obj, loc_params, vol_plugin, NULL, type_id, H5P_DEFAULT, 
+    if (NULL == (dt = H5VL_datatype_commit(obj, loc_params, vol_plugin->cls, NULL, type_id, H5P_DEFAULT, 
                                            tcpl_id, tapl_id, H5AC_dxpl_id, H5_REQUEST_NULL)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to commit datatype")
 
@@ -347,6 +351,10 @@ H5Tcommit_anon(hid_t loc_id, hid_t type_id, hid_t tcpl_id, hid_t tapl_id)
     if (H5I_register_aux(type_id, vol_plugin) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "can't attach vol info to ID")
 
+    vol_plugin->nrefs ++;
+    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTINC, FAIL, "unable to increment ref count on VOL plugin")
+
 done:
     FUNC_LEAVE_API(ret_value)
 } /* end H5Tcommit_anon() */
@@ -620,7 +628,7 @@ H5Topen2(hid_t loc_id, const char *name, hid_t tapl_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the datatype through the VOL */
-    if(NULL == (dt = H5VL_datatype_open(obj, loc_params, vol_plugin, name, tapl_id, 
+    if(NULL == (dt = H5VL_datatype_open(obj, loc_params, vol_plugin->cls, name, tapl_id, 
                                         H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open datatype")
 
@@ -630,7 +638,7 @@ H5Topen2(hid_t loc_id, const char *name, hid_t tapl_id)
 
 done:
     if (ret_value < 0 && dt)
-        if(H5VL_datatype_close (dt, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_datatype_close (dt, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Topen2() */
@@ -694,7 +702,7 @@ H5Tget_create_plist(hid_t dtype_id)
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier")
 
         /* get the rest of the plist through the VOL */
-        if(H5VL_datatype_get(type, vol_plugin, H5VL_DATATYPE_GET_TCPL, 
+        if(H5VL_datatype_get(type, vol_plugin->cls, H5VL_DATATYPE_GET_TCPL, 
                              H5AC_ind_dxpl_id, H5_REQUEST_NULL, &ret_value) < 0)
             HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "unable to get datatype")
     } /* end if */
@@ -959,7 +967,7 @@ H5VL_create_datatype(void *dt_obj, H5VL_t *vol_plugin, hbool_t app_ref)
     FUNC_ENTER_NOAPI(FAIL)
 
     /* get required buf size for encoding the datatype */
-    if(H5VL_datatype_get(dt_obj, vol_plugin, H5VL_DATATYPE_GET_BINARY, 
+    if(H5VL_datatype_get(dt_obj, vol_plugin->cls, H5VL_DATATYPE_GET_BINARY, 
                          H5AC_dxpl_id, H5_REQUEST_NULL, &nalloc, NULL, 0) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to get datatype serialized size")
 
@@ -968,19 +976,19 @@ H5VL_create_datatype(void *dt_obj, H5VL_t *vol_plugin, hbool_t app_ref)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate space for datatype")
 
     /* get binary description of the datatype */
-    if(H5VL_datatype_get(dt_obj, vol_plugin, H5VL_DATATYPE_GET_BINARY, 
+    if(H5VL_datatype_get(dt_obj, vol_plugin->cls, H5VL_DATATYPE_GET_BINARY, 
                          H5AC_dxpl_id, H5_REQUEST_NULL, &nalloc, buf, (size_t)nalloc) < 0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to get serialized datatype")
 
-    if(NULL == (dt = H5T_decode(buf)))
+            if(NULL == (dt = H5T_decode((const unsigned char *)buf)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "can't decode datatype")
     dt->vol_obj = dt_obj;
 
     H5MM_free(buf);
 
     /* Get an atom for the datatype with the VOL information as the auxilary struct*/
-    if((ret_value = H5I_register2(H5I_DATATYPE, dt, vol_plugin, app_ref)) < 0)
-	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize file handle")
+    if((ret_value = H5VL_register_id(H5I_DATATYPE, dt, vol_plugin, app_ref)) < 0)
+	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize datatype handle")
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -1010,10 +1018,15 @@ H5T_close_datatype(void *type, H5VL_t *vol_plugin)
     FUNC_ENTER_NOAPI_NOINIT
 
     /* Close the datatype through the VOL*/
-    if (NULL != dt->vol_obj)
-        if((ret_value = H5VL_datatype_close(dt->vol_obj, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
+    if (NULL != dt->vol_obj) {
+        if((ret_value = H5VL_datatype_close(dt->vol_obj, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL)) < 0)
             HGOTO_ERROR(H5E_DATATYPE, H5E_CLOSEERROR, FAIL, "unable to close datatype")
 
+        /* decrement ref count on VOL ID */
+        if(H5VL_free_id(vol_plugin) < 0)
+            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTDEC, FAIL, "unable to decrement ref count on VOL plugin")
+    }
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5T_close_datatype() */
diff --git a/src/H5Tdeprec.c b/src/H5Tdeprec.c
index addbdfe..51c55f4 100644
--- a/src/H5Tdeprec.c
+++ b/src/H5Tdeprec.c
@@ -178,7 +178,7 @@ H5Tcommit1(hid_t loc_id, const char *name, hid_t type_id)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* commit the datatype through the VOL */
-    if (NULL == (dt = H5VL_datatype_commit(obj, loc_params, vol_plugin, name, type_id, 
+    if (NULL == (dt = H5VL_datatype_commit(obj, loc_params, vol_plugin->cls, name, type_id, 
                                            H5P_LINK_CREATE_DEFAULT, H5P_DATATYPE_CREATE_DEFAULT, 
                                            H5P_DATATYPE_ACCESS_DEFAULT, H5AC_dxpl_id, H5_REQUEST_NULL)))
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to commit datatype")
@@ -192,6 +192,10 @@ H5Tcommit1(hid_t loc_id, const char *name, hid_t type_id)
     if (H5I_register_aux(type_id, vol_plugin) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "can't attach vol info to ID")
 
+    vol_plugin->nrefs ++;
+    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTINC, FAIL, "unable to increment ref count on VOL plugin")
+
 done:
     FUNC_LEAVE_API(ret_value)
 } /* end H5Tcommit1() */
@@ -240,7 +244,7 @@ H5Topen1(hid_t loc_id, const char *name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
     /* Create the datatype through the VOL */
-    if(NULL == (dt = H5VL_datatype_open(obj, loc_params, vol_plugin, name, 
+    if(NULL == (dt = H5VL_datatype_open(obj, loc_params, vol_plugin->cls, name, 
                                         H5P_DATATYPE_ACCESS_DEFAULT, H5AC_dxpl_id, H5_REQUEST_NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to open datatype")
 
@@ -250,7 +254,7 @@ H5Topen1(hid_t loc_id, const char *name)
 
 done:
     if (ret_value < 0 && dt)
-        if(H5VL_datatype_close (dt, vol_plugin, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
+        if(H5VL_datatype_close (dt, vol_plugin->cls, H5AC_dxpl_id, H5_REQUEST_NULL) < 0)
             HDONE_ERROR(H5E_SYM, H5E_CLOSEERROR, FAIL, "unable to release dataset")
     FUNC_LEAVE_API(ret_value)
 } /* end H5Topen1() */
diff --git a/src/H5Tprivate.h b/src/H5Tprivate.h
index 217a0d6..3722af8 100644
--- a/src/H5Tprivate.h
+++ b/src/H5Tprivate.h
@@ -141,7 +141,6 @@ H5_DLL herr_t H5T_set_latest_version(H5T_t *dt);
 H5_DLL herr_t H5T_patch_file(H5T_t *dt, H5F_t *f);
 H5_DLL htri_t H5T_is_variable_str(const H5T_t *dt);
 H5_DLL void * H5T_get_named_type(const H5T_t *dt);
-H5_DLL hid_t H5VL_create_datatype(void *dt_obj, H5VL_t *vol_plugin, hbool_t app_ref);
 H5_DLL herr_t H5T_set_vol_object(H5T_t *type, void *vol_obj);
 
 /* Reference specific functions */
diff --git a/src/H5VL.c b/src/H5VL.c
index 485bc57..aa0775a 100644
--- a/src/H5VL.c
+++ b/src/H5VL.c
@@ -52,9 +52,9 @@ static herr_t H5VL_free_cls(H5VL_class_t *cls);
 /* Local Variables */
 /*******************/
 typedef struct {
-    const H5VL_class_t *vol_cls;
+    const char *name;
     hid_t ret_id;
-} H5VL_is_registered_ud_t;
+} H5VL_get_plugin_ud_t;
 
 /* VOL ID class */
 static const H5I_class_t H5I_VOL_CLS[1] = {{
@@ -306,6 +306,7 @@ H5VLinitialize(hid_t plugin_id, hid_t vipl_id)
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_API(FAIL)
+    H5TRACE2("e", "ii", plugin_id, vipl_id);
 
     /* Check args */
     if(NULL == (cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
@@ -338,6 +339,7 @@ H5VLterminate(hid_t plugin_id, hid_t vtpl_id)
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_API(FAIL)
+    H5TRACE2("e", "ii", plugin_id, vtpl_id);
 
     /* Check args */
     if(NULL == (cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
@@ -367,21 +369,21 @@ done:
  *-------------------------------------------------------------------------
  */
 static int
-H5VL__is_registered_cb(void *obj, hid_t id, void *_op_data)
+H5VL__get_plugin_cb(void *obj, hid_t id, void *_op_data)
 {
-    H5VL_is_registered_ud_t *op_data = (H5VL_is_registered_ud_t *)_op_data; /* User data for callback */
+    H5VL_get_plugin_ud_t *op_data = (H5VL_get_plugin_ud_t *)_op_data; /* User data for callback */
     H5VL_class_t *cls = (H5VL_class_t *)obj;
-    int ret_value;     /* Callback return value */
+    int ret_value = H5_ITER_CONT;     /* Callback return value */
 
     FUNC_ENTER_STATIC_NOERR
 
-    if(cls->value == op_data->vol_cls->value) {
+    if(0 == strcmp(cls->name, op_data->name)) {
         op_data->ret_id = id;
         ret_value = H5_ITER_STOP;
     }
 
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5VL__is_registered_cb() */
+} /* end H5VL__get_plugin_cb() */
 
 
 /*-------------------------------------------------------------------------
@@ -399,19 +401,19 @@ H5VL__is_registered_cb(void *obj, hid_t id, void *_op_data)
  *-------------------------------------------------------------------------
  */
 htri_t
-H5VLis_registered(const H5VL_class_t *cls)
+H5VLis_registered(const char *name)
 {
-    H5VL_is_registered_ud_t op_data;
+    H5VL_get_plugin_ud_t op_data;
     htri_t ret_value = FALSE;     /* Return value */
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE1("t", "*x", cls);
+    H5TRACE1("t", "*s", name);
 
     op_data.ret_id = FAIL;
-    op_data.vol_cls = cls;
+    op_data.name = name;
 
     /* Check arguments */
-    if(H5I_iterate(H5I_VOL, H5VL__is_registered_cb, &op_data, TRUE) < 0)
+    if(H5I_iterate(H5I_VOL, H5VL__get_plugin_cb, &op_data, TRUE) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_BADITER, FAIL, "can't iterate over VOL ids")
 
     if(op_data.ret_id != FAIL)
@@ -436,18 +438,19 @@ done:
  *-------------------------------------------------------------------------
  */
 hid_t
-H5VLget_plugin_id(const H5VL_class_t *cls)
+H5VLget_plugin_id(const char *name)
 {
-    H5VL_is_registered_ud_t op_data;
+    H5VL_get_plugin_ud_t op_data;
     hid_t ret_value = FAIL;     /* Return value */
 
     FUNC_ENTER_API(FAIL)
+    H5TRACE1("i", "*s", name);
 
     op_data.ret_id = FAIL;
-    op_data.vol_cls = cls;
+    op_data.name = name;
 
     /* Check arguments */
-    if(H5I_iterate(H5I_VOL, H5VL__is_registered_cb, &op_data, TRUE) < 0)
+    if(H5I_iterate(H5I_VOL, H5VL__get_plugin_cb, &op_data, TRUE) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_BADITER,FAIL, "can't iterate over VOL ids")
 
     if(op_data.ret_id != FAIL) {
@@ -477,14 +480,14 @@ done:
  *-------------------------------------------------------------------------
  */
 ssize_t
-H5VLget_plugin_name(hid_t id, char *name/*out*/, size_t size)
+H5VLget_plugin_name(hid_t obj_id, char *name/*out*/, size_t size)
 {
     ssize_t    ret_value;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE3("Zs", "ixz", id, name, size);
+    H5TRACE3("Zs", "ixz", obj_id, name, size);
 
-    if((ret_value = H5VL_get_plugin_name(id, name, size)) < 0)
+    if((ret_value = H5VL_get_plugin_name(obj_id, name, size)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "Can't get plugin name")
 
 done:
@@ -511,9 +514,10 @@ H5VLclose(hid_t vol_id)
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_API(FAIL)
+    H5TRACE1("e", "i", vol_id);
 
     /* Check args */
-    if(NULL == H5I_object_verify(vol_id,H5I_VOL))
+    if(NULL == H5I_object_verify(vol_id, H5I_VOL))
 	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
     if(H5I_dec_app_ref(vol_id) < 0)
@@ -538,19 +542,25 @@ done:
  *---------------------------------------------------------------------------
  */
 hid_t
-H5VLobject_register(void *obj, H5I_type_t obj_type, const H5VL_class_t *cls)
+H5VLobject_register(void *obj, H5I_type_t obj_type, hid_t plugin_id)
 {
     H5VL_t  *vol_plugin;        /* VOL plugin information */
+    H5VL_class_t *vol_cls = NULL;
     hid_t ret_value = FAIL;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE3("i", "*xIt*x", obj, obj_type, cls);
+    H5TRACE3("i", "*xIti", obj, obj_type, plugin_id);
+
+    if(NULL == obj)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object to register")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
     /* Build the vol plugin struct */
     if(NULL == (vol_plugin = (H5VL_t *)H5MM_calloc(sizeof(H5VL_t))))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
-    vol_plugin->cls = cls;
-    vol_plugin->nrefs = 1;
+    vol_plugin->cls = vol_cls;
+    vol_plugin->id = plugin_id;
 
     if ((ret_value = H5VL_object_register(obj, obj_type, vol_plugin, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize dataset handle")
@@ -575,29 +585,25 @@ done:
  *---------------------------------------------------------------------------
  */
 herr_t
-H5VLget_object(hid_t obj_id, void **obj, H5VL_t **vol_plugin)
+H5VLget_object(hid_t obj_id, void **obj)
 {
-    H5VL_t *temp_vol;
+    H5VL_t *vol_plugin;
     hid_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE3("e", "i**x**x", obj_id, obj, vol_plugin);
+    H5TRACE2("e", "i**x", obj_id, obj);
 
     /* Check args */
     if(!obj)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object pointer")
 
     /* get the plugin pointer */
-    if (NULL == (temp_vol = (H5VL_t *)H5I_get_aux(obj_id)))
+    if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    if(NATIVE == temp_vol->cls->value)
+    if(NATIVE == vol_plugin->cls->value)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "cannot call public function on library type")
 
-    /* if the user requested the plugin pointer, return it */
-    if(vol_plugin)
-        *vol_plugin = temp_vol;
-
     if(NULL == (*obj = H5VL_get_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain a valid object")
 
@@ -620,16 +626,21 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VLattr_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+H5VLattr_create(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, const char *name, 
                 hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, void **req)
 {
-    void *ret_value = NULL;  /* Return value */
+    H5VL_class_t *vol_cls = NULL;
+    void *ret_value = NULL; /* Return value */
 
     FUNC_ENTER_API(NULL)
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
-    if(NULL == (ret_value = H5VL_attr_create(obj, loc_params, vol_plugin, name, acpl_id, aapl_id, dxpl_id, req)))
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a VOL plugin ID")
+
+    if(NULL == (ret_value = H5VL_attr_create(obj, loc_params, vol_cls, name, 
+                                             acpl_id, aapl_id, dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to create attribute")
 
 done:
@@ -651,16 +662,21 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VLattr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+H5VLattr_open(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, const char *name, 
               hid_t aapl_id, hid_t dxpl_id, void **req)
 {
-    void *ret_value;  /* Return value */
+    H5VL_class_t *vol_cls = NULL;
+    void *ret_value = NULL; /* Return value */
 
     FUNC_ENTER_API(NULL)
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
-    if(NULL == (ret_value = H5VL_attr_open(obj, loc_params, vol_plugin, name, aapl_id, dxpl_id, req)))
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a VOL plugin ID")
+
+    if(NULL == (ret_value = H5VL_attr_open(obj, loc_params, vol_cls, name, aapl_id, 
+                                           dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to open attribute")
 
 done:
@@ -682,15 +698,19 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t H5VLattr_read(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, void *buf, hid_t dxpl_id, void **req)
+herr_t H5VLattr_read(void *attr, hid_t plugin_id, hid_t mem_type_id, void *buf, hid_t dxpl_id, void **req)
 {
+    H5VL_class_t *vol_cls = NULL;
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
 
-    if (NULL == attr || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_attr_read(attr, vol_plugin, mem_type_id, buf, dxpl_id, req)) < 0)
+    if (NULL == attr)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
+
+    if((ret_value = H5VL_attr_read(attr, vol_cls, mem_type_id, buf, dxpl_id, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to read attribute")
 
 done:
@@ -711,15 +731,19 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t H5VLattr_write(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, const void *buf, hid_t dxpl_id, void **req)
+herr_t H5VLattr_write(void *attr, hid_t plugin_id, hid_t mem_type_id, const void *buf, hid_t dxpl_id, void **req)
 {
+    H5VL_class_t *vol_cls = NULL;
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
 
-    if (NULL == attr || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_attr_write(attr, vol_plugin, mem_type_id, buf, dxpl_id, req)) < 0)
+    if (NULL == attr)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
+
+    if((ret_value = H5VL_attr_write(attr, vol_cls, mem_type_id, buf, dxpl_id, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to write attribute")
 
 done:
@@ -741,21 +765,24 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLattr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, 
+H5VLattr_get(void *obj, hid_t plugin_id, H5VL_attr_get_t get_type, 
              hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE6("e", "*x*xVai**xx", obj, vol_plugin, get_type, dxpl_id, req, arguments);
+    H5TRACE6("e", "*xiVai**xx", obj, plugin_id, get_type, dxpl_id, req, arguments);
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
     /* Bypass the H5VLint layer */
-    if(NULL == vol_plugin->cls->attr_cls.get)
+    if(NULL == vol_cls->attr_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr get' method")
-    if((ret_value = (vol_plugin->cls->attr_cls.get)(obj, get_type, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->attr_cls.get)(obj, get_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "Unable to get attribute information")
 
 done:
@@ -777,22 +804,25 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLattr_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
+H5VLattr_specific(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, 
                   H5VL_attr_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE7("e", "*xx*xVbi**xx", obj, loc_params, vol_plugin, specific_type,
+    H5TRACE7("e", "*xxiVbi**xx", obj, loc_params, plugin_id, specific_type,
              dxpl_id, req, arguments);
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
     /* Bypass the H5VLint layer */
-    if(NULL == vol_plugin->cls->attr_cls.specific)
+    if(NULL == vol_cls->attr_cls.specific)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr specific' method")
-    if((ret_value = (vol_plugin->cls->attr_cls.specific)
+    if((ret_value = (vol_cls->attr_cls.specific)
         (obj, loc_params, specific_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute attribute specific callback")
 
@@ -815,20 +845,23 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLattr_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, va_list arguments)
+H5VLattr_optional(void *obj, hid_t plugin_id, hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE5("e", "*x*xi**xx", obj, vol_plugin, dxpl_id, req, arguments);
+    H5TRACE5("e", "*xii**xx", obj, plugin_id, dxpl_id, req, arguments);
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
     /* Have to bypass the H5VLint layer due to unknown val_list arguments */
-    if(NULL == vol_plugin->cls->attr_cls.optional)
+    if(NULL == vol_cls->attr_cls.optional)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr optional' method")
-    if((ret_value = (vol_plugin->cls->attr_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->attr_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute attribute optional callback")
 
 done:
@@ -850,16 +883,20 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLattr_close(void *attr, H5VL_t *vol_plugin, hid_t dxpl_id, void **req)
+H5VLattr_close(void *attr, hid_t plugin_id, hid_t dxpl_id, void **req)
 {
+    H5VL_class_t *vol_cls = NULL;
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE4("e", "*x*xi**x", attr, vol_plugin, dxpl_id, req);
+    H5TRACE4("e", "*xii**x", attr, plugin_id, dxpl_id, req);
 
-    if (NULL == attr || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_attr_close(attr, vol_plugin, dxpl_id, req)) < 0)
+    if (NULL == attr)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
+
+    if((ret_value = H5VL_attr_close(attr, vol_cls, dxpl_id, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to close attribute")
 
 done:
@@ -881,16 +918,20 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VLdatatype_commit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+H5VLdatatype_commit(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, const char *name, 
                      hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t dxpl_id, void **req)
 {
-    void *ret_value = NULL;              /* Return value */
+    H5VL_class_t *vol_cls = NULL;
+    void *ret_value = NULL; /* Return value */
 
     FUNC_ENTER_API(NULL)
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
-    if(NULL == (ret_value = H5VL_datatype_commit(obj, loc_params, vol_plugin, name, type_id, 
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a VOL plugin ID")
+
+    if(NULL == (ret_value = H5VL_datatype_commit(obj, loc_params, vol_cls, name, type_id, 
                                                  lcpl_id, tcpl_id, tapl_id, dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to commit datatype")
 
@@ -913,16 +954,21 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VLdatatype_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+H5VLdatatype_open(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, const char *name, 
                    hid_t tapl_id, hid_t dxpl_id, void **req)
 {
-    void *ret_value = NULL;              /* Return value */
+    H5VL_class_t *vol_cls = NULL;
+    void *ret_value = NULL; /* Return value */
 
     FUNC_ENTER_API(NULL)
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
-    if(NULL == (ret_value = H5VL_datatype_open(obj, loc_params, vol_plugin, name, tapl_id, dxpl_id, req)))
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a VOL plugin ID")
+
+    if(NULL == (ret_value = H5VL_datatype_open(obj, loc_params, vol_cls, name, 
+                                               tapl_id, dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to open datatype")
 
 done:
@@ -944,21 +990,24 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLdatatype_specific(void *obj, H5VL_t *vol_plugin, H5VL_datatype_specific_t specific_type, 
+H5VLdatatype_specific(void *obj, hid_t plugin_id, H5VL_datatype_specific_t specific_type, 
                       hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE6("e", "*x*xVfi**xx", obj, vol_plugin, specific_type, dxpl_id, req,
+    H5TRACE6("e", "*xiVfi**xx", obj, plugin_id, specific_type, dxpl_id, req,
              arguments);
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
-    if(NULL == vol_plugin->cls->datatype_cls.specific)
+    if(NULL == vol_cls->datatype_cls.specific)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `datatype specific' method")
-    if((ret_value = (vol_plugin->cls->datatype_cls.specific)
+    if((ret_value = (vol_cls->datatype_cls.specific)
         (obj, specific_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute datatype specific callback")
 
@@ -981,19 +1030,22 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLdatatype_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, va_list arguments)
+H5VLdatatype_optional(void *obj, hid_t plugin_id, hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE5("e", "*x*xi**xx", obj, vol_plugin, dxpl_id, req, arguments);
+    H5TRACE5("e", "*xii**xx", obj, plugin_id, dxpl_id, req, arguments);
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
-    if(NULL == vol_plugin->cls->datatype_cls.optional)
+    if(NULL == vol_cls->datatype_cls.optional)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `datatype optional' method")
-    if((ret_value = (vol_plugin->cls->datatype_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->datatype_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute datatype optional callback")
 
 done:
@@ -1015,21 +1067,24 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLdatatype_get(void *obj, H5VL_t *vol_plugin, H5VL_datatype_get_t get_type, 
+H5VLdatatype_get(void *obj, hid_t plugin_id, H5VL_datatype_get_t get_type, 
                  hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE6("e", "*x*xVei**xx", obj, vol_plugin, get_type, dxpl_id, req, arguments);
+    H5TRACE6("e", "*xiVei**xx", obj, plugin_id, get_type, dxpl_id, req, arguments);
 
-    if(NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if(NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
     /* Bypass the H5VLint layer */
-    if(NULL == vol_plugin->cls->datatype_cls.get)
+    if(NULL == vol_cls->datatype_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `datatype get' method")
-    if((ret_value = (vol_plugin->cls->datatype_cls.get)(obj, get_type, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->datatype_cls.get)(obj, get_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "Unable to execute datatype get callback")
 
 done:
@@ -1051,16 +1106,20 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLdatatype_close(void *dt, H5VL_t *vol_plugin, hid_t dxpl_id, void **req)
+H5VLdatatype_close(void *dt, hid_t plugin_id, hid_t dxpl_id, void **req)
 {
-    herr_t		ret_value = SUCCEED;    /* Return value */
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE4("e", "*x*xi**x", dt, vol_plugin, dxpl_id, req);
+    H5TRACE4("e", "*xii**x", dt, plugin_id, dxpl_id, req);
 
-    if (NULL == dt || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_datatype_close(dt, vol_plugin, dxpl_id, req)) < 0)
+    if (NULL == dt)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
+
+    if((ret_value = H5VL_datatype_close(dt, vol_cls, dxpl_id, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to close datatype")
 
 done:
@@ -1082,16 +1141,20 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VLdataset_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+H5VLdataset_create(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, const char *name, 
                     hid_t dcpl_id, hid_t dapl_id, hid_t dxpl_id, void **req)
 {
-    void *ret_value; /* Return value */
+    H5VL_class_t *vol_cls = NULL;
+    void *ret_value = NULL; /* Return value */
 
     FUNC_ENTER_API(NULL)
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
-    if(NULL == (ret_value = H5VL_dataset_create(obj, loc_params, vol_plugin, name, 
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a VOL plugin ID")
+
+    if(NULL == (ret_value = H5VL_dataset_create(obj, loc_params, vol_cls, name, 
                                                 dcpl_id, dapl_id, dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to create dataset")
 
@@ -1114,16 +1177,20 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VLdataset_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+H5VLdataset_open(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, const char *name, 
                   hid_t dapl_id, hid_t dxpl_id, void **req)
 {
-    void *ret_value; /* Return value */
+    H5VL_class_t *vol_cls = NULL;
+    void *ret_value = NULL; /* Return value */
 
     FUNC_ENTER_API(NULL)
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
-    if(NULL == (ret_value = H5VL_dataset_open(obj, loc_params, vol_plugin, name, dapl_id, dxpl_id, req)))
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a VOL plugin ID")
+
+    if(NULL == (ret_value = H5VL_dataset_open(obj, loc_params, vol_cls, name, dapl_id, dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to open dataset")
 
 done:
@@ -1145,18 +1212,22 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLdataset_read(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, 
+H5VLdataset_read(void *dset, hid_t plugin_id, hid_t mem_type_id, hid_t mem_space_id, 
                   hid_t file_space_id, hid_t plist_id, void *buf, void **req)
 {
+    H5VL_class_t *vol_cls = NULL;
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE8("e", "*x*xiiii*x**x", dset, vol_plugin, mem_type_id, mem_space_id,
+    H5TRACE8("e", "*xiiiii*x**x", dset, plugin_id, mem_type_id, mem_space_id,
              file_space_id, plist_id, buf, req);
 
-    if (NULL == dset || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_dataset_read(dset, vol_plugin, mem_type_id, mem_space_id, file_space_id, 
+    if (NULL == dset)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
+
+    if((ret_value = H5VL_dataset_read(dset, vol_cls, mem_type_id, mem_space_id, file_space_id, 
                                       plist_id, buf, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to read dataset")
 
@@ -1179,18 +1250,22 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLdataset_write(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, 
+H5VLdataset_write(void *dset, hid_t plugin_id, hid_t mem_type_id, hid_t mem_space_id, 
                    hid_t file_space_id, hid_t plist_id, const void *buf, void **req)
 {
+    H5VL_class_t *vol_cls = NULL;
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE8("e", "*x*xiiii*x**x", dset, vol_plugin, mem_type_id, mem_space_id,
+    H5TRACE8("e", "*xiiiii*x**x", dset, plugin_id, mem_type_id, mem_space_id,
              file_space_id, plist_id, buf, req);
 
-    if (NULL == dset || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_dataset_write(dset, vol_plugin, mem_type_id, mem_space_id, file_space_id, 
+    if (NULL == dset)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
+
+    if((ret_value = H5VL_dataset_write(dset, vol_cls, mem_type_id, mem_space_id, file_space_id, 
                                        plist_id, buf, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to write dataset")
 
@@ -1213,22 +1288,24 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLdataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, 
+H5VLdataset_get(void *dset, hid_t plugin_id, H5VL_dataset_get_t get_type, 
                 hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE6("e", "*x*xVci**xx", dset, vol_plugin, get_type, dxpl_id, req,
-             arguments);
+    H5TRACE6("e", "*xiVci**xx", dset, plugin_id, get_type, dxpl_id, req, arguments);
 
-    if (NULL == dset || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if (NULL == dset)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
     /* Bypass the H5VLint layer */
-    if(NULL == vol_plugin->cls->dataset_cls.get)
+    if(NULL == vol_cls->dataset_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dataset get' method")
-    if((ret_value = (vol_plugin->cls->dataset_cls.get)(dset, get_type, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->dataset_cls.get)(dset, get_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "Unable to execute dataset get callback")
 
 done:
@@ -1250,21 +1327,24 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLdataset_specific(void *obj, H5VL_t *vol_plugin, H5VL_dataset_specific_t specific_type, 
+H5VLdataset_specific(void *obj, hid_t plugin_id, H5VL_dataset_specific_t specific_type, 
                       hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE6("e", "*x*xVdi**xx", obj, vol_plugin, specific_type, dxpl_id, req,
+    H5TRACE6("e", "*xiVdi**xx", obj, plugin_id, specific_type, dxpl_id, req,
              arguments);
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
-    if(NULL == vol_plugin->cls->dataset_cls.specific)
+    if(NULL == vol_cls->dataset_cls.specific)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dataset specific' method")
-    if((ret_value = (vol_plugin->cls->dataset_cls.specific)
+    if((ret_value = (vol_cls->dataset_cls.specific)
         (obj, specific_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute dataset specific callback")
 
@@ -1287,19 +1367,22 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLdataset_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, va_list arguments)
+H5VLdataset_optional(void *obj, hid_t plugin_id, hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE5("e", "*x*xi**xx", obj, vol_plugin, dxpl_id, req, arguments);
+    H5TRACE5("e", "*xii**xx", obj, plugin_id, dxpl_id, req, arguments);
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
-    if(NULL == vol_plugin->cls->dataset_cls.optional)
+    if(NULL == vol_cls->dataset_cls.optional)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dataset optional' method")
-    if((ret_value = (vol_plugin->cls->dataset_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->dataset_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute dataset optional callback")
 
 done:
@@ -1321,16 +1404,20 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLdataset_close(void *dset, H5VL_t *vol_plugin, hid_t dxpl_id, void **req)
+H5VLdataset_close(void *dset, hid_t plugin_id, hid_t dxpl_id, void **req)
 {
+    H5VL_class_t *vol_cls = NULL;
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE4("e", "*x*xi**x", dset, vol_plugin, dxpl_id, req);
+    H5TRACE4("e", "*xii**x", dset, plugin_id, dxpl_id, req);
+
+    if (NULL == dset)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
-    if (NULL == dset || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_dataset_close(dset, vol_plugin, dxpl_id, req)) < 0)
+    if((ret_value = H5VL_dataset_close(dset, vol_cls, dxpl_id, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to close dataset")
 
 done:
@@ -1352,14 +1439,27 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VLfile_create(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fcpl_id, 
-                hid_t fapl_id, hid_t dxpl_id, void **req)
+H5VLfile_create(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, 
+                hid_t dxpl_id, void **req)
 {
-    void	       *ret_value;             /* Return value */
+    H5P_genplist_t     *plist;                 /* Property list pointer */
+    hid_t               plugin_id;             /* VOL plugin identigier attached to fapl_id */
+    H5VL_class_t       *vol_cls = NULL;
+    void	       *ret_value = NULL;      /* Return value */
 
     FUNC_ENTER_API(NULL)
 
-    if(NULL == (ret_value = H5VL_file_create(vol_plugin, name, flags, fcpl_id, fapl_id, dxpl_id, req)))
+    /* get the VOL info from the fapl */
+    if(NULL == (plist = (H5P_genplist_t *)H5I_object(fapl_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list")
+    if(H5P_get(plist, H5F_ACS_VOL_ID_NAME, &plugin_id) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get vol plugin ID")
+
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a VOL plugin ID")
+
+    if(NULL == (ret_value = H5VL_file_create(vol_cls, name, flags, fcpl_id, fapl_id, 
+                                             dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to create file")
 
 done:
@@ -1381,13 +1481,25 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VLfile_open(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fapl_id, hid_t dxpl_id, void **req)
+H5VLfile_open(const char *name, unsigned flags, hid_t fapl_id, hid_t dxpl_id, void **req)
 {
-    void	       *ret_value;             /* Return value */
+    H5P_genplist_t     *plist;                 /* Property list pointer */
+    hid_t               plugin_id;             /* VOL plugin id attached to fapl_id */
+    H5VL_class_t       *vol_cls = NULL;
+    void	       *ret_value = NULL;      /* Return value */
 
     FUNC_ENTER_API(NULL)
 
-    if(NULL == (ret_value = H5VL_file_open(vol_plugin, name, flags, fapl_id, dxpl_id, req)))
+    /* get the VOL info from the fapl */
+    if(NULL == (plist = (H5P_genplist_t *)H5I_object(fapl_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list")
+    if(H5P_get(plist, H5F_ACS_VOL_ID_NAME, &plugin_id) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get vol plugin ID")
+
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a VOL plugin ID")
+
+    if(NULL == (ret_value = H5VL_file_open(vol_cls, name, flags, fapl_id, dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to create file")
 
 done:
@@ -1409,22 +1521,24 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLfile_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, 
+H5VLfile_get(void *file, hid_t plugin_id, H5VL_file_get_t get_type, 
              hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE6("e", "*x*xVgi**xx", file, vol_plugin, get_type, dxpl_id, req,
-             arguments);
+    H5TRACE6("e", "*xiVgi**xx", file, plugin_id, get_type, dxpl_id, req, arguments);
 
-    if(NULL == file || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if(NULL == file)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
     /* Bypass the H5VLint layer */
-    if(NULL == vol_plugin->cls->file_cls.get)
+    if(NULL == vol_cls->file_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file get' method")
-    if((ret_value = (vol_plugin->cls->file_cls.get)(file, get_type, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->file_cls.get)(file, get_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "Unable to execute file get callback")
 
 done:
@@ -1446,19 +1560,19 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLfile_specific(void *file, H5VL_t *vol_plugin, H5VL_file_specific_t specific_type, 
+H5VLfile_specific(void *file, hid_t plugin_id, H5VL_file_specific_t specific_type, 
                   hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE6("e", "*x*xVhi**xx", file, vol_plugin, specific_type, dxpl_id, req,
+    H5TRACE6("e", "*xiVhi**xx", file, plugin_id, specific_type, dxpl_id, req,
              arguments);
 
     if(specific_type == H5VL_FILE_IS_ACCESSIBLE) {
         H5P_genplist_t     *plist;          /* Property list pointer */
         hid_t               vol_id;         /* VOL plugin identigier attached to fapl_id */
-        H5VL_class_t       *vol_cls;        /* VOL class of vol_id */
         hid_t               fapl_id;
 
         fapl_id = va_arg (arguments, hid_t);
@@ -1477,12 +1591,14 @@ H5VLfile_specific(void *file, H5VL_t *vol_plugin, H5VL_file_specific_t specific_
             HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "specific failed")
     }
     else {
-        if(NULL == file || NULL == vol_plugin || NULL == vol_plugin->cls)
-            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+        if(NULL == file)
+            HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+        if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
-        if(NULL == vol_plugin->cls->file_cls.specific)
+        if(NULL == vol_cls->file_cls.specific)
             HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file specific' method")
-        if((ret_value = (vol_plugin->cls->file_cls.specific)
+        if((ret_value = (vol_cls->file_cls.specific)
             (file, specific_type, dxpl_id, req, arguments)) < 0)
             HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute file specific callback")
     }
@@ -1505,19 +1621,22 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLfile_optional(void *file, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, va_list arguments)
+H5VLfile_optional(void *file, hid_t plugin_id, hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE5("e", "*x*xi**xx", file, vol_plugin, dxpl_id, req, arguments);
+    H5TRACE5("e", "*xii**xx", file, plugin_id, dxpl_id, req, arguments);
 
-    if(NULL == file || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if(NULL == file)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
-    if(NULL == vol_plugin->cls->file_cls.optional)
+    if(NULL == vol_cls->file_cls.optional)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file optional' method")
-    if((ret_value = (vol_plugin->cls->file_cls.optional)(file, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->file_cls.optional)(file, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute file optional callback")
 
 done:
@@ -1539,16 +1658,20 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLfile_close(void *file, H5VL_t *vol_plugin, hid_t dxpl_id, void **req)
+H5VLfile_close(void *file, hid_t plugin_id, hid_t dxpl_id, void **req)
 {
+    H5VL_class_t *vol_cls = NULL;
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE4("e", "*x*xi**x", file, vol_plugin, dxpl_id, req);
+    H5TRACE4("e", "*xii**x", file, plugin_id, dxpl_id, req);
+
+    if(NULL == file)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
-    if(NULL == file || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_file_close(file, vol_plugin, dxpl_id, req)) < 0)
+    if((ret_value = H5VL_file_close(file, vol_cls, dxpl_id, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to close file")
 
 done:
@@ -1570,16 +1693,20 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VLgroup_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+H5VLgroup_create(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, const char *name, 
                  hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, void **req)
 {
+    H5VL_class_t *vol_cls = NULL;
     void *ret_value = NULL; /* Return value */
 
     FUNC_ENTER_API(NULL)
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
-    if(NULL == (ret_value = H5VL_group_create(obj, loc_params, vol_plugin, name, 
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a VOL plugin ID")
+
+    if(NULL == (ret_value = H5VL_group_create(obj, loc_params, vol_cls, name, 
                                               gcpl_id, gapl_id, dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to create group")
 
@@ -1602,16 +1729,20 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VLgroup_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+H5VLgroup_open(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, const char *name, 
                 hid_t gapl_id, hid_t dxpl_id, void **req)
 {
-    void *ret_value; /* Return value */
+    H5VL_class_t *vol_cls = NULL;
+    void *ret_value = NULL; /* Return value */
 
     FUNC_ENTER_API(NULL)
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
-    if(NULL == (ret_value = H5VL_group_open(obj, loc_params, vol_plugin, name, 
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a VOL plugin ID")
+
+    if(NULL == (ret_value = H5VL_group_open(obj, loc_params, vol_cls, name, 
                                               gapl_id, dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to open group")
 
@@ -1634,21 +1765,24 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLgroup_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, 
+H5VLgroup_get(void *obj, hid_t plugin_id, H5VL_group_get_t get_type, 
               hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE6("e", "*x*xVii**xx", obj, vol_plugin, get_type, dxpl_id, req, arguments);
+    H5TRACE6("e", "*xiVii**xx", obj, plugin_id, get_type, dxpl_id, req, arguments);
 
-    if(NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if(NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
     /* Bypass the H5VLint layer */
-    if(NULL == vol_plugin->cls->group_cls.get)
+    if(NULL == vol_cls->group_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `group get' method")
-    if((ret_value = (vol_plugin->cls->group_cls.get)(obj, get_type, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->group_cls.get)(obj, get_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "Unable to execute group get callback")
 
 done:
@@ -1670,21 +1804,24 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLgroup_specific(void *obj, H5VL_t *vol_plugin, H5VL_group_specific_t specific_type, 
+H5VLgroup_specific(void *obj, hid_t plugin_id, H5VL_group_specific_t specific_type, 
                       hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE6("e", "*x*xVji**xx", obj, vol_plugin, specific_type, dxpl_id, req,
+    H5TRACE6("e", "*xiVji**xx", obj, plugin_id, specific_type, dxpl_id, req,
              arguments);
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
-    if(NULL == vol_plugin->cls->group_cls.specific)
+    if(NULL == vol_cls->group_cls.specific)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `group specific' method")
-    if((ret_value = (vol_plugin->cls->group_cls.specific)
+    if((ret_value = (vol_cls->group_cls.specific)
         (obj, specific_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute group specific callback")
 
@@ -1707,19 +1844,22 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLgroup_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, va_list arguments)
+H5VLgroup_optional(void *obj, hid_t plugin_id, hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE5("e", "*x*xi**xx", obj, vol_plugin, dxpl_id, req, arguments);
+    H5TRACE5("e", "*xii**xx", obj, plugin_id, dxpl_id, req, arguments);
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
-    if(NULL == vol_plugin->cls->group_cls.optional)
+    if(NULL == vol_cls->group_cls.optional)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `group optional' method")
-    if((ret_value = (vol_plugin->cls->group_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->group_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute group optional callback")
 
 done:
@@ -1741,16 +1881,20 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLgroup_close(void *grp, H5VL_t *vol_plugin, hid_t dxpl_id, void **req)
+H5VLgroup_close(void *grp, hid_t plugin_id, hid_t dxpl_id, void **req)
 {
+    H5VL_class_t *vol_cls = NULL;
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE4("e", "*x*xi**x", grp, vol_plugin, dxpl_id, req);
+    H5TRACE4("e", "*xii**x", grp, plugin_id, dxpl_id, req);
 
-    if(NULL == grp || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_group_close(grp, vol_plugin, dxpl_id, req)) < 0)
+    if(NULL == grp)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
+
+    if((ret_value = H5VL_group_close(grp, vol_cls, dxpl_id, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to close group")
 
 done:
@@ -1772,17 +1916,21 @@ done:
  */
 herr_t
 H5VLlink_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params_t loc_params, 
-                 H5VL_t *vol_plugin, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req)
+                 hid_t plugin_id, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req)
 {
-    herr_t               ret_value = SUCCEED;  /* Return value */
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE8("e", "Vk*xx*xiii**x", create_type, obj, loc_params, vol_plugin,
-             lcpl_id, lapl_id, dxpl_id, req);
+    H5TRACE8("e", "Vk*xxiiii**x", create_type, obj, loc_params, plugin_id, lcpl_id,
+             lapl_id, dxpl_id, req);
 
-    if(NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_link_create(create_type, obj, loc_params, vol_plugin, lcpl_id, lapl_id, dxpl_id, req)) < 0)
+    if(NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
+
+    if((ret_value = H5VL_link_create(create_type, obj, loc_params, vol_cls, lcpl_id, lapl_id, dxpl_id, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to create link")
 
 done:
@@ -1802,18 +1950,25 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-H5_DLL herr_t H5VLlink_copy(void *src_obj, H5VL_loc_params_t loc_params1, void *dst_obj, 
-                            H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin, 
-                            hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req)
+herr_t
+H5VLlink_copy(void *src_obj, H5VL_loc_params_t loc_params1, void *dst_obj, 
+              H5VL_loc_params_t loc_params2, hid_t plugin_id, 
+              hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req)
 {
-    herr_t               ret_value = SUCCEED;  /* Return value */
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
+    H5TRACE9("e", "*xx*xxiiii**x", src_obj, loc_params1, dst_obj, loc_params2,
+             plugin_id, lcpl_id, lapl_id, dxpl_id, req);
+
+    if(NULL == src_obj || NULL == dst_obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
-    if(NULL == src_obj || NULL == dst_obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-            if((ret_value = H5VL_link_copy(src_obj, loc_params1, dst_obj, loc_params2, vol_plugin, 
-                                           lcpl_id, lapl_id, dxpl_id, req)) < 0)
+    if((ret_value = H5VL_link_copy(src_obj, loc_params1, dst_obj, loc_params2, vol_cls, 
+                                   lcpl_id, lapl_id, dxpl_id, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to copy object")
 
 done:
@@ -1833,17 +1988,24 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-H5_DLL herr_t H5VLlink_move(void *src_obj, H5VL_loc_params_t loc_params1, void *dst_obj, 
-                            H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin, 
-                            hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req)
+herr_t
+H5VLlink_move(void *src_obj, H5VL_loc_params_t loc_params1, void *dst_obj, 
+              H5VL_loc_params_t loc_params2, hid_t plugin_id, 
+              hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req)
 {
-    herr_t               ret_value = SUCCEED;  /* Return value */
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
+    H5TRACE9("e", "*xx*xxiiii**x", src_obj, loc_params1, dst_obj, loc_params2,
+             plugin_id, lcpl_id, lapl_id, dxpl_id, req);
 
-    if(NULL == src_obj || NULL == dst_obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_link_move(src_obj, loc_params1, dst_obj, loc_params2, vol_plugin, 
+    if(NULL == src_obj || NULL == dst_obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
+
+    if((ret_value = H5VL_link_move(src_obj, loc_params1, dst_obj, loc_params2, vol_cls, 
                                    lcpl_id, lapl_id, dxpl_id, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to move object")
 
@@ -1867,21 +2029,24 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLlink_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_link_get_t get_type, 
+H5VLlink_get(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, H5VL_link_get_t get_type, 
               hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE7("e", "*xx*xVli**xx", obj, loc_params, vol_plugin, get_type, dxpl_id,
-             req, arguments);
+    H5TRACE7("e", "*xxiVli**xx", obj, loc_params, plugin_id, get_type, dxpl_id, req,
+             arguments);
 
-    if(NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if(NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
-    if(NULL == vol_plugin->cls->link_cls.get)
+    if(NULL == vol_cls->link_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link get' method")
-    if((ret_value = (vol_plugin->cls->link_cls.get)
+    if((ret_value = (vol_cls->link_cls.get)
         (obj, loc_params, get_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute link get callback")
 
@@ -1904,22 +2069,25 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLlink_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
+H5VLlink_specific(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, 
                   H5VL_link_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE7("e", "*xx*xVmi**xx", obj, loc_params, vol_plugin, specific_type,
+    H5TRACE7("e", "*xxiVmi**xx", obj, loc_params, plugin_id, specific_type,
              dxpl_id, req, arguments);
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
     /* Bypass the H5VLint layer */
-    if(NULL == vol_plugin->cls->link_cls.specific)
+    if(NULL == vol_cls->link_cls.specific)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link specific' method")
-    if((ret_value = (vol_plugin->cls->link_cls.specific)
+    if((ret_value = (vol_cls->link_cls.specific)
         (obj, loc_params, specific_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute link specific callback")
 
@@ -1942,20 +2110,23 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLlink_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, va_list arguments)
+H5VLlink_optional(void *obj, hid_t plugin_id, hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE5("e", "*x*xi**xx", obj, vol_plugin, dxpl_id, req, arguments);
+    H5TRACE5("e", "*xii**xx", obj, plugin_id, dxpl_id, req, arguments);
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
     /* Have to bypass the H5VLint layer due to unknown val_list arguments */
-    if(NULL == vol_plugin->cls->link_cls.optional)
+    if(NULL == vol_cls->link_cls.optional)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link optional' method")
-    if((ret_value = (vol_plugin->cls->link_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->link_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute link optional callback")
 
 done:
@@ -1977,16 +2148,20 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VLobject_open(void *obj, H5VL_loc_params_t params, H5VL_t *vol_plugin, H5I_type_t *opened_type,
+H5VLobject_open(void *obj, H5VL_loc_params_t params, hid_t plugin_id, H5I_type_t *opened_type,
                 hid_t dxpl_id, void **req)
 {
-    void *ret_value;              /* Return value */
+    H5VL_class_t *vol_cls = NULL;
+    void *ret_value = NULL; /* Return value */
 
     FUNC_ENTER_API(NULL)
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object/VOL class pointer")
-    if(NULL == (ret_value = H5VL_object_open(obj, params, vol_plugin, opened_type, dxpl_id, req)))
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a VOL plugin ID")
+
+    if(NULL == (ret_value = H5VL_object_open(obj, params, vol_cls, opened_type, dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "unable to create group")
 
 done:
@@ -2008,22 +2183,28 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLobject_copy(void *src_obj, H5VL_loc_params_t loc_params1, H5VL_t *vol_plugin1, const char *src_name, 
-                void *dst_obj, H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin2, const char *dst_name, 
+H5VLobject_copy(void *src_obj, H5VL_loc_params_t loc_params1, hid_t plugin_id1, const char *src_name, 
+                void *dst_obj, H5VL_loc_params_t loc_params2, hid_t plugin_id2, const char *dst_name, 
                 hid_t ocpypl_id, hid_t lcpl_id, hid_t dxpl_id, void **req)
 {
+    H5VL_class_t *vol_cls1 = NULL;
+    H5VL_class_t *vol_cls2 = NULL;
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE12("e", "*xx*x*s*xx*x*siii**x", src_obj, loc_params1, vol_plugin1,
-             src_name, dst_obj, loc_params2, vol_plugin2, dst_name, ocpypl_id,
+    H5TRACE12("e", "*xxi*s*xxi*siii**x", src_obj, loc_params1, plugin_id1,
+             src_name, dst_obj, loc_params2, plugin_id2, dst_name, ocpypl_id,
              lcpl_id, dxpl_id, req);
 
-    if(NULL == src_obj || NULL == dst_obj || NULL == vol_plugin1 || 
-       NULL == vol_plugin2 || NULL == vol_plugin1->cls || NULL == vol_plugin2->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
-    if((ret_value = H5VL_object_copy(src_obj, loc_params1, vol_plugin1, src_name, 
-                                     dst_obj, loc_params2, vol_plugin2, dst_name,
+    if(NULL == src_obj || NULL == dst_obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls1 = (H5VL_class_t *)H5I_object_verify(plugin_id1, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
+    if(NULL == (vol_cls2 = (H5VL_class_t *)H5I_object_verify(plugin_id2, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
+
+    if((ret_value = H5VL_object_copy(src_obj, loc_params1, vol_cls1, src_name, 
+                                     dst_obj, loc_params2, vol_cls2, dst_name,
                                      ocpypl_id, lcpl_id, dxpl_id, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "unable to move object")
 
@@ -2047,21 +2228,24 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLobject_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_get_t get_type, 
+H5VLobject_get(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, H5VL_object_get_t get_type, 
                hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE7("e", "*xx*xVni**xx", obj, loc_params, vol_plugin, get_type, dxpl_id,
-             req, arguments);
+    H5TRACE7("e", "*xxiVni**xx", obj, loc_params, plugin_id, get_type, dxpl_id, req,
+             arguments);
 
-    if(NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if(NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
-    if(NULL == vol_plugin->cls->object_cls.get)
+    if(NULL == vol_cls->object_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object get' method")
-    if((ret_value = (vol_plugin->cls->object_cls.get)
+    if((ret_value = (vol_cls->object_cls.get)
         (obj, loc_params, get_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute object get callback")
 
@@ -2084,22 +2268,25 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLobject_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
+H5VLobject_specific(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, 
                     H5VL_object_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE7("e", "*xx*xVoi**xx", obj, loc_params, vol_plugin, specific_type,
+    H5TRACE7("e", "*xxiVoi**xx", obj, loc_params, plugin_id, specific_type,
              dxpl_id, req, arguments);
 
-    if(NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if(NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
     /* Bypass the H5VLint layer */
-    if(NULL == vol_plugin->cls->object_cls.specific)
+    if(NULL == vol_cls->object_cls.specific)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object specific' method")
-    if((ret_value = (vol_plugin->cls->object_cls.specific)
+    if((ret_value = (vol_cls->object_cls.specific)
         (obj, loc_params, specific_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute object specific callback")
 
@@ -2122,20 +2309,23 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLobject_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, va_list arguments)
+H5VLobject_optional(void *obj, hid_t plugin_id, hid_t dxpl_id, void **req, va_list arguments)
 {
-    herr_t            ret_value = SUCCEED;
+    H5VL_class_t *vol_cls = NULL;
+    herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE5("e", "*x*xi**xx", obj, vol_plugin, dxpl_id, req, arguments);
+    H5TRACE5("e", "*xii**xx", obj, plugin_id, dxpl_id, req, arguments);
 
-    if (NULL == obj || NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object/VOL class pointer")
+    if (NULL == obj)
+	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object")
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
     /* Have to bypass the H5VLint layer due to unknown val_list arguments */
-    if(NULL == vol_plugin->cls->object_cls.optional)
+    if(NULL == vol_cls->object_cls.optional)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object optional' method")
-    if((ret_value = (vol_plugin->cls->object_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->object_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute object optional callback")
 
 done:
@@ -2157,16 +2347,18 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLrequest_cancel(void **req, H5VL_t *vol_plugin, H5ES_status_t *status)
+H5VLrequest_cancel(void **req, hid_t plugin_id, H5ES_status_t *status)
 {
+    H5VL_class_t *vol_cls = NULL;
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE3("e", "**x*x*Es", req, vol_plugin, status);
+    H5TRACE3("e", "**xi*Es", req, plugin_id, status);
+
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
-    if(NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid request/VOL class pointer")
-    if((ret_value = H5VL_request_cancel(req, vol_plugin, status)) < 0)
+    if((ret_value = H5VL_request_cancel(req, vol_cls, status)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to cancel request")
 
 done:
@@ -2188,16 +2380,18 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLrequest_test(void **req, H5VL_t *vol_plugin, H5ES_status_t *status)
+H5VLrequest_test(void **req, hid_t plugin_id, H5ES_status_t *status)
 {
+    H5VL_class_t *vol_cls = NULL;
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE3("e", "**x*x*Es", req, vol_plugin, status);
+    H5TRACE3("e", "**xi*Es", req, plugin_id, status);
 
-    if(NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid request/VOL class pointer")
-    if((ret_value = H5VL_request_test(req, vol_plugin, status)) < 0)
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
+
+    if((ret_value = H5VL_request_test(req, vol_cls, status)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to test request")
 
 done:
@@ -2219,16 +2413,18 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLrequest_wait(void **req, H5VL_t *vol_plugin, H5ES_status_t *status)
+H5VLrequest_wait(void **req, hid_t plugin_id, H5ES_status_t *status)
 {
+    H5VL_class_t *vol_cls = NULL;
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_API(FAIL)
-    H5TRACE3("e", "**x*x*Es", req, vol_plugin, status);
+    H5TRACE3("e", "**xi*Es", req, plugin_id, status);
+
+    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object_verify(plugin_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a VOL plugin ID")
 
-    if(NULL == vol_plugin || NULL == vol_plugin->cls)
-	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid request/VOL class pointer")
-    if((ret_value = H5VL_request_wait(req, vol_plugin, status)) < 0)
+    if((ret_value = H5VL_request_wait(req, vol_cls, status)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "unable to wait on request")
 
 done:
diff --git a/src/H5VLint.c b/src/H5VLint.c
index bfdd35e..ecb95f4 100644
--- a/src/H5VLint.c
+++ b/src/H5VLint.c
@@ -119,6 +119,76 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5VL_register_id
+ *
+ * Purpose:	Wrapper to register an object ID with a VOL aux struct 
+ *              and increment ref count on VOL plugin ID
+ *
+ * Return:	Success:	Positive Identifier
+ *		Failure:	A negative value.
+ *
+ * Programmer:	Mohamad Chaarawi
+ *              August, 2014
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5VL_register_id(H5I_type_t type, const void *object, H5VL_t *vol_plugin, hbool_t app_ref)
+{
+    hid_t ret_value = FAIL;
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Check arguments */
+    HDassert(object);
+    HDassert(vol_plugin);
+
+    if((ret_value = H5I_register2(type, object, vol_plugin, app_ref)) < 0)
+	HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize handle")
+
+    vol_plugin->nrefs ++;
+    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
+        HGOTO_ERROR(H5E_ATOM, H5E_CANTINC, FAIL, "unable to increment ref count on VOL plugin")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL_register_id() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5VL_free_id
+ *
+ * Purpose:	Wrapper to register an object ID with a VOL aux struct 
+ *              and increment ref count on VOL plugin ID
+ *
+ * Return:	Success:	Positive Identifier
+ *		Failure:	A negative value.
+ *
+ * Programmer:	Mohamad Chaarawi
+ *              August, 2014
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5VL_free_id(H5VL_t *vol_plugin)
+{
+    herr_t ret_value = SUCCEED;
+
+    FUNC_ENTER_NOAPI(SUCCEED)
+
+    /* Check arguments */
+    HDassert(vol_plugin);
+
+    vol_plugin->nrefs --;
+    if(H5I_dec_ref(vol_plugin->id) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTDEC, FAIL, "unable to decrement ref count on VOL plugin")
+    if (0 == vol_plugin->nrefs)
+        vol_plugin = (H5VL_t *)H5MM_xfree(vol_plugin);
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL_free_id() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5VL_fapl_open
  *
  * Purpose:	Mark a vol as used by a file access property list
@@ -320,22 +390,22 @@ H5VL_object_register(void *obj, H5I_type_t obj_type, H5VL_t *vol_plugin, hbool_t
     /* Get an atom for the object and attach VOL information and free function to the ID */
     switch(obj_type) {
         case H5I_FILE:
-            if((ret_value = H5I_register2(obj_type, obj, vol_plugin, app_ref)) < 0)
+            if((ret_value = H5VL_register_id(obj_type, obj, vol_plugin, app_ref)) < 0)
                 HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize file handle")
             break;
 
         case H5I_ATTR:
-            if((ret_value = H5I_register2(obj_type, obj, vol_plugin, app_ref)) < 0)
+            if((ret_value = H5VL_register_id(obj_type, obj, vol_plugin, app_ref)) < 0)
                 HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize attribute handle")
             break;
 
         case H5I_GROUP:
-            if((ret_value = H5I_register2(obj_type, obj, vol_plugin, app_ref)) < 0)
+            if((ret_value = H5VL_register_id(obj_type, obj, vol_plugin, app_ref)) < 0)
                 HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize group handle")
             break;
 
         case H5I_DATASET:
-            if((ret_value = H5I_register2(obj_type, obj, vol_plugin, app_ref)) < 0)
+            if((ret_value = H5VL_register_id(obj_type, obj, vol_plugin, app_ref)) < 0)
                 HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize dataset handle")
             break;
 
@@ -417,7 +487,7 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VL_attr_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+H5VL_attr_create(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, const char *name, 
                  hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, void **req)
 {
     void *ret_value;  /* Return value */
@@ -425,18 +495,14 @@ H5VL_attr_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, co
     FUNC_ENTER_NOAPI(NULL)
 
     /* check if the corresponding VOL create callback exists */
-    if(NULL == vol_plugin->cls->attr_cls.create)
+    if(NULL == vol_cls->attr_cls.create)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `attr create' method")
 
     /* call the corresponding VOL create callback */
-    if(NULL == (ret_value = (vol_plugin->cls->attr_cls.create) 
+    if(NULL == (ret_value = (vol_cls->attr_cls.create) 
                 (obj, loc_params, name, acpl_id, aapl_id, dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "create failed")
 
-    vol_plugin->nrefs ++;
-    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINC, NULL, "unable to increment ref count on VOL plugin")
-
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_attr_create() */
@@ -457,7 +523,7 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VL_attr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+H5VL_attr_open(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, const char *name, 
                hid_t aapl_id, hid_t dxpl_id, void **req)
 {
     void *ret_value;  /* Return value */
@@ -465,17 +531,14 @@ H5VL_attr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, cons
     FUNC_ENTER_NOAPI(NULL)
 
     /* check if the type specific corresponding VOL open callback exists */
-    if(NULL == vol_plugin->cls->attr_cls.open)
+    if(NULL == vol_cls->attr_cls.open)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `attr open' method")
+
     /* call the corresponding VOL open callback */
-    if(NULL == (ret_value = (vol_plugin->cls->attr_cls.open) 
+    if(NULL == (ret_value = (vol_cls->attr_cls.open) 
                 (obj, loc_params, name, aapl_id, dxpl_id, req)))
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPENOBJ, NULL, "attribute open failed")
 
-    vol_plugin->nrefs ++;
-    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINC, NULL, "unable to increment ref count on VOL plugin")
-
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_attr_open() */
@@ -495,16 +558,16 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t H5VL_attr_read(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, void *buf, 
+herr_t H5VL_attr_read(void *attr, const H5VL_class_t *vol_cls, hid_t mem_type_id, void *buf, 
                       hid_t dxpl_id, void **req)
 {
     herr_t              ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->attr_cls.read)
+    if(NULL == vol_cls->attr_cls.read)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr read' method")
-    if((ret_value = (vol_plugin->cls->attr_cls.read)(attr, mem_type_id, buf, dxpl_id, req)) < 0)
+    if((ret_value = (vol_cls->attr_cls.read)(attr, mem_type_id, buf, dxpl_id, req)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "read failed")
 
 done:
@@ -526,16 +589,16 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t H5VL_attr_write(void *attr, H5VL_t *vol_plugin, hid_t mem_type_id, const void *buf, 
+herr_t H5VL_attr_write(void *attr, const H5VL_class_t *vol_cls, hid_t mem_type_id, const void *buf, 
                        hid_t dxpl_id, void **req)
 {
     herr_t              ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->attr_cls.write)
+    if(NULL == vol_cls->attr_cls.write)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr write' method")
-    if((ret_value = (vol_plugin->cls->attr_cls.write)(attr, mem_type_id, buf, dxpl_id, req)) < 0)
+    if((ret_value = (vol_cls->attr_cls.write)(attr, mem_type_id, buf, dxpl_id, req)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "write failed")
 
 done:
@@ -558,7 +621,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_attr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, 
+H5VL_attr_get(void *obj, const H5VL_class_t *vol_cls, H5VL_attr_get_t get_type, 
               hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
@@ -566,11 +629,11 @@ H5VL_attr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type,
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->attr_cls.get)
+    if(NULL == vol_cls->attr_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr get' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->attr_cls.get)
+    if((ret_value = (vol_cls->attr_cls.get)
         (obj, get_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end (arguments);
@@ -595,7 +658,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_attr_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
+H5VL_attr_specific(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, 
                    H5VL_attr_specific_t specific_type, hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
@@ -603,11 +666,11 @@ H5VL_attr_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin,
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->attr_cls.specific)
+    if(NULL == vol_cls->attr_cls.specific)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr specific' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->attr_cls.specific)
+    if((ret_value = (vol_cls->attr_cls.specific)
         (obj, loc_params, specific_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute attribute specific callback")
     va_end (arguments);
@@ -632,18 +695,18 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_attr_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, ...)
+H5VL_attr_optional(void *obj, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->attr_cls.optional)
+    if(NULL == vol_cls->attr_cls.optional)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr optional' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->attr_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->attr_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute attribute optional callback")
     va_end (arguments);
 
@@ -667,23 +730,17 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_attr_close(void *attr, H5VL_t *vol_plugin, hid_t dxpl_id, void **req)
+H5VL_attr_close(void *attr, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req)
 {
     herr_t              ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
             
-    if(NULL == vol_plugin->cls->attr_cls.close)
+    if(NULL == vol_cls->attr_cls.close)
         HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `attr close' method")
-    if((ret_value = (vol_plugin->cls->attr_cls.close)(attr, dxpl_id, req)) < 0)
+    if((ret_value = (vol_cls->attr_cls.close)(attr, dxpl_id, req)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "close failed")
 
-    vol_plugin->nrefs --;
-    if(H5I_dec_ref(vol_plugin->id) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTDEC, FAIL, "unable to decrement ref count on VOL plugin")
-    if (0 == vol_plugin->nrefs)
-        vol_plugin = (H5VL_t *)H5MM_xfree(vol_plugin);
-
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_attr_close() */
@@ -704,7 +761,7 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VL_datatype_commit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+H5VL_datatype_commit(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, const char *name, 
                      hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, 
                      hid_t dxpl_id, void **req)
 {
@@ -713,18 +770,14 @@ H5VL_datatype_commit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin
     FUNC_ENTER_NOAPI(NULL)
 
     /* check if the corresponding VOL commit callback exists */
-    if(NULL == vol_plugin->cls->datatype_cls.commit)
+    if(NULL == vol_cls->datatype_cls.commit)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `datatype commit' method")
 
     /* call the corresponding VOL commit callback */
-    if(NULL == (ret_value = (vol_plugin->cls->datatype_cls.commit) 
+    if(NULL == (ret_value = (vol_cls->datatype_cls.commit) 
         (obj, loc_params, name, type_id, lcpl_id, tcpl_id, tapl_id, dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "commit failed")
 
-    vol_plugin->nrefs ++;
-    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINC, NULL, "unable to increment ref count on VOL plugin")
-
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_datatype_commit() */
@@ -745,7 +798,7 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VL_datatype_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+H5VL_datatype_open(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, const char *name, 
                    hid_t tapl_id, hid_t dxpl_id, void **req)
 {
     void *ret_value = NULL;              /* Return value */
@@ -753,18 +806,14 @@ H5VL_datatype_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin,
     FUNC_ENTER_NOAPI(NULL)
 
     /* check if the type specific corresponding VOL open callback exists */
-    if(NULL == vol_plugin->cls->datatype_cls.open)
+    if(NULL == vol_cls->datatype_cls.open)
         HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "no datatype open callback");
 
     /* call the corresponding VOL open callback */
-    if(NULL == (ret_value = (vol_plugin->cls->datatype_cls.open)
+    if(NULL == (ret_value = (vol_cls->datatype_cls.open)
                 (obj, loc_params, name, tapl_id, dxpl_id, req)))
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPENOBJ, NULL, "open failed")
 
-    vol_plugin->nrefs ++;
-    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINC, NULL, "unable to increment ref count on VOL plugin")
-
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_datatype_open() */
@@ -785,7 +834,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_datatype_get(void *obj, H5VL_t *vol_plugin, H5VL_datatype_get_t get_type, 
+H5VL_datatype_get(void *obj, const H5VL_class_t *vol_cls, H5VL_datatype_get_t get_type, 
                   hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
@@ -793,10 +842,10 @@ H5VL_datatype_get(void *obj, H5VL_t *vol_plugin, H5VL_datatype_get_t get_type,
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->datatype_cls.get)
+    if(NULL == vol_cls->datatype_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `datatype get' method")
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->datatype_cls.get)(obj, get_type, dxpl_id, 
+    if((ret_value = (vol_cls->datatype_cls.get)(obj, get_type, dxpl_id, 
                                                         req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end (arguments);
@@ -821,7 +870,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_datatype_specific(void *obj, H5VL_t *vol_plugin, H5VL_datatype_specific_t specific_type, 
+H5VL_datatype_specific(void *obj, const H5VL_class_t *vol_cls, H5VL_datatype_specific_t specific_type, 
                        hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
@@ -829,11 +878,11 @@ H5VL_datatype_specific(void *obj, H5VL_t *vol_plugin, H5VL_datatype_specific_t s
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->datatype_cls.specific)
+    if(NULL == vol_cls->datatype_cls.specific)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `datatype specific' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->datatype_cls.specific)
+    if((ret_value = (vol_cls->datatype_cls.specific)
         (obj, specific_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute datatype specific callback")
     va_end (arguments);
@@ -858,18 +907,18 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_datatype_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, ...)
+H5VL_datatype_optional(void *obj, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->datatype_cls.optional)
+    if(NULL == vol_cls->datatype_cls.optional)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `datatype optional' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->datatype_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->datatype_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute datatype optional callback")
     va_end (arguments);
 
@@ -892,26 +941,20 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_datatype_close(void *dt, H5VL_t *vol_plugin, hid_t dxpl_id, void **req)
+H5VL_datatype_close(void *dt, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req)
 {
     herr_t		ret_value = SUCCEED;    /* Return value */
 
     FUNC_ENTER_NOAPI(FAIL)
 
     /* check if the corresponding VOL close callback exists */
-    if(NULL == vol_plugin->cls->datatype_cls.close)
+    if(NULL == vol_cls->datatype_cls.close)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `datatype close' method")
 
     /* call the corresponding VOL close callback */
-    if((ret_value = (vol_plugin->cls->datatype_cls.close)(dt, dxpl_id, req)) < 0)
+    if((ret_value = (vol_cls->datatype_cls.close)(dt, dxpl_id, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "close failed")
 
-    if(H5I_dec_ref(vol_plugin->id) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTDEC, FAIL, "unable to decrement ref count on VOL plugin")
-    vol_plugin->nrefs --;
-    if (0 == vol_plugin->nrefs)
-        vol_plugin = (H5VL_t *)H5MM_xfree(vol_plugin);
-
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_datatype_close() */
@@ -932,7 +975,7 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VL_dataset_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+H5VL_dataset_create(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, const char *name, 
                     hid_t dcpl_id, hid_t dapl_id, hid_t dxpl_id, void **req)
 {
     void *ret_value; /* Return value */
@@ -940,18 +983,14 @@ H5VL_dataset_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin,
     FUNC_ENTER_NOAPI(NULL)
 
     /* check if the corresponding VOL create callback exists */
-    if(NULL == vol_plugin->cls->dataset_cls.create)
+    if(NULL == vol_cls->dataset_cls.create)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `dataset create' method")
 
     /* call the corresponding VOL create callback */
-    if(NULL == (ret_value = (vol_plugin->cls->dataset_cls.create)
+    if(NULL == (ret_value = (vol_cls->dataset_cls.create)
                 (obj, loc_params, name, dcpl_id, dapl_id, dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "create failed")
 
-    vol_plugin->nrefs ++;
-    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINC, NULL, "unable to increment ref count on VOL plugin")
-
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_dataset_create() */
@@ -972,7 +1011,7 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VL_dataset_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+H5VL_dataset_open(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, const char *name, 
                   hid_t dapl_id, hid_t dxpl_id, void **req)
 {
     void *ret_value; /* Return value */
@@ -980,18 +1019,14 @@ H5VL_dataset_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, c
     FUNC_ENTER_NOAPI(NULL)
 
     /* check if the type specific corresponding VOL open callback exists */
-    if(NULL == vol_plugin->cls->dataset_cls.open)
+    if(NULL == vol_cls->dataset_cls.open)
         HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no 'dset open' method")
 
     /* call the corresponding VOL open callback */
-    if(NULL == (ret_value = (vol_plugin->cls->dataset_cls.open)
+    if(NULL == (ret_value = (vol_cls->dataset_cls.open)
                 (obj, loc_params, name, dapl_id, dxpl_id, req)))
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPENOBJ, NULL, "open failed")
 
-    vol_plugin->nrefs ++;
-    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINC, NULL, "unable to increment ref count on VOL plugin")
-
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_dataset_open() */
@@ -1012,16 +1047,16 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t 
-H5VL_dataset_read(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, 
+H5VL_dataset_read(void *dset, const H5VL_class_t *vol_cls, hid_t mem_type_id, hid_t mem_space_id, 
                   hid_t file_space_id, hid_t plist_id, void *buf, void **req)
 {
     herr_t              ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->dataset_cls.read)
+    if(NULL == vol_cls->dataset_cls.read)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dataset read' method")
-    if((ret_value = (vol_plugin->cls->dataset_cls.read)
+    if((ret_value = (vol_cls->dataset_cls.read)
         (dset, mem_type_id, mem_space_id, file_space_id, plist_id, buf, req)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_READERROR, FAIL, "read failed")
 
@@ -1045,16 +1080,16 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t 
-H5VL_dataset_write(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, 
+H5VL_dataset_write(void *dset, const H5VL_class_t *vol_cls, hid_t mem_type_id, hid_t mem_space_id, 
                    hid_t file_space_id, hid_t plist_id, const void *buf, void **req)
 {
     herr_t              ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->dataset_cls.write)
+    if(NULL == vol_cls->dataset_cls.write)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dataset write' method")
-    if((ret_value = (vol_plugin->cls->dataset_cls.write)
+    if((ret_value = (vol_cls->dataset_cls.write)
         (dset, mem_type_id, mem_space_id, file_space_id, plist_id, buf, req)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_WRITEERROR, FAIL, "write failed")
 
@@ -1078,7 +1113,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_dataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, 
+H5VL_dataset_get(void *dset, const H5VL_class_t *vol_cls, H5VL_dataset_get_t get_type, 
                  hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
@@ -1086,11 +1121,11 @@ H5VL_dataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type,
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->dataset_cls.get)
+    if(NULL == vol_cls->dataset_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dataset get' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->dataset_cls.get)(dset, get_type, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->dataset_cls.get)(dset, get_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end (arguments);
 
@@ -1114,7 +1149,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_dataset_specific(void *obj, H5VL_t *vol_plugin, H5VL_dataset_specific_t specific_type, 
+H5VL_dataset_specific(void *obj, const H5VL_class_t *vol_cls, H5VL_dataset_specific_t specific_type, 
                        hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
@@ -1122,11 +1157,11 @@ H5VL_dataset_specific(void *obj, H5VL_t *vol_plugin, H5VL_dataset_specific_t spe
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->dataset_cls.specific)
+    if(NULL == vol_cls->dataset_cls.specific)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dataset specific' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->dataset_cls.specific)
+    if((ret_value = (vol_cls->dataset_cls.specific)
         (obj, specific_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute dataset specific callback")
     va_end (arguments);
@@ -1151,18 +1186,18 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_dataset_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, ...)
+H5VL_dataset_optional(void *obj, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->dataset_cls.optional)
+    if(NULL == vol_cls->dataset_cls.optional)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dataset optional' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->dataset_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->dataset_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute dataset optional callback")
     va_end (arguments);
 
@@ -1186,26 +1221,18 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_dataset_close(void *dset, H5VL_t *vol_plugin, hid_t dxpl_id, void **req)
+H5VL_dataset_close(void *dset, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req)
 {
     herr_t              ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->dataset_cls.close)
+    if(NULL == vol_cls->dataset_cls.close)
         HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `dset close' method")
-    if((ret_value = (vol_plugin->cls->dataset_cls.close)(dset, dxpl_id, req)) < 0)
+    if((ret_value = (vol_cls->dataset_cls.close)(dset, dxpl_id, req)) < 0)
             HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "close failed")
 
 done:
-    /* MSC - Weird thing for datasets and filters:
-       Always decrement the ref count on the vol for datasets, since
-       the ID is removed even if the close fails */
-    vol_plugin->nrefs --;
-    if(H5I_dec_ref(vol_plugin->id) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTDEC, FAIL, "unable to decrement ref count on VOL plugin")
-    if (0 == vol_plugin->nrefs)
-        vol_plugin = (H5VL_t *)H5MM_xfree(vol_plugin);
 
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_dataset_close() */
@@ -1226,26 +1253,13 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VL_file_create(H5VL_t **plugin, const char *name, unsigned flags, hid_t fcpl_id, 
+H5VL_file_create(const H5VL_class_t *vol_cls, const char *name, unsigned flags, hid_t fcpl_id, 
                  hid_t fapl_id, hid_t dxpl_id, void **req)
 {
-    H5P_genplist_t     *plist;                 /* Property list pointer */
-    hid_t               vol_id;                /* VOL plugin identigier attached to fapl_id */
-    H5VL_class_t       *vol_cls = NULL;        /* VOL class of vol_id */
-    H5VL_t             *vol_plugin = NULL;     /* the public VOL struct */
-    void	       *ret_value;             /* Return value */
+    void *ret_value = NULL;             /* Return value */
 
     FUNC_ENTER_NOAPI(NULL)
 
-    /* get the VOL info from the fapl */
-    if(NULL == (plist = (H5P_genplist_t *)H5I_object(fapl_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list")
-    if(H5P_get(plist, H5F_ACS_VOL_ID_NAME, &vol_id) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get vol plugin ID")
-
-    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object(vol_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a VOL ID")
-
     /* check if the corresponding VOL create callback exists */
     if(NULL == vol_cls->file_cls.create)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `file create' method")
@@ -1253,17 +1267,6 @@ H5VL_file_create(H5VL_t **plugin, const char *name, unsigned flags, hid_t fcpl_i
     if(NULL == (ret_value = (vol_cls->file_cls.create)(name, flags, fcpl_id, fapl_id, dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "create failed")
 
-    /* Build the vol plugin struct */
-    if(NULL == (*plugin = (H5VL_t *)H5MM_calloc(sizeof(H5VL_t))))
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
-
-    vol_plugin = *plugin;
-    vol_plugin->cls = vol_cls;
-    vol_plugin->nrefs = 1;
-    vol_plugin->id = vol_id;
-    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINC, NULL, "unable to increment ref count on VOL plugin")
-
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_file_create() */
@@ -1284,26 +1287,13 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VL_file_open(H5VL_t **plugin, const char *name, unsigned flags, hid_t fapl_id, 
+H5VL_file_open(const H5VL_class_t *vol_cls, const char *name, unsigned flags, hid_t fapl_id, 
                hid_t dxpl_id, void **req)
 {
-    H5P_genplist_t     *plist;                 /* Property list pointer */
-    hid_t               vol_id;                /* VOL plugin identigier attached to fapl_id */
-    H5VL_class_t       *vol_cls = NULL;        /* VOL class of vol_id */
-    H5VL_t             *vol_plugin = NULL;     /* the public VOL struct */
-    void	       *ret_value;             /* Return value */
+    void *ret_value = NULL;             /* Return value */
 
     FUNC_ENTER_NOAPI(NULL)
 
-    /* get the VOL info from the fapl */
-    if(NULL == (plist = (H5P_genplist_t *)H5I_object(fapl_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list")
-    if(H5P_get(plist, H5F_ACS_VOL_ID_NAME, &vol_id) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get vol plugin ID")
-
-    if(NULL == (vol_cls = (H5VL_class_t *)H5I_object(vol_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a VOL ID")
-
     /* check if the corresponding VOL create callback exists */
     if(NULL == vol_cls->file_cls.open)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `file open' method")
@@ -1311,17 +1301,6 @@ H5VL_file_open(H5VL_t **plugin, const char *name, unsigned flags, hid_t fapl_id,
     if(NULL == (ret_value = (vol_cls->file_cls.open)(name, flags, fapl_id, dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "open failed")
 
-    /* Build the vol plugin struct */
-    if(NULL == (*plugin = (H5VL_t *)H5MM_calloc(sizeof(H5VL_t))))
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
-
-    vol_plugin = *plugin;
-    vol_plugin->cls = vol_cls;
-    vol_plugin->nrefs = 1;
-    vol_plugin->id = vol_id;
-    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINC, NULL, "unable to increment ref count on VOL plugin")
-
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_file_open() */
@@ -1342,7 +1321,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_file_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, 
+H5VL_file_get(void *file, const H5VL_class_t *vol_cls, H5VL_file_get_t get_type, 
               hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
@@ -1350,11 +1329,11 @@ H5VL_file_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type,
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->file_cls.get)
+    if(NULL == vol_cls->file_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file get' method")
 
     va_start(arguments, req);
-    if((ret_value = (vol_plugin->cls->file_cls.get)(file, get_type, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->file_cls.get)(file, get_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end(arguments);
 
@@ -1377,7 +1356,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_file_specific(void *file, H5VL_t *vol_plugin, H5VL_file_specific_t specific_type, 
+H5VL_file_specific(void *file, const H5VL_class_t *vol_cls, H5VL_file_specific_t specific_type, 
                    hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
@@ -1388,7 +1367,6 @@ H5VL_file_specific(void *file, H5VL_t *vol_plugin, H5VL_file_specific_t specific
     if(specific_type == H5VL_FILE_IS_ACCESSIBLE) {
         H5P_genplist_t     *plist;          /* Property list pointer */
         hid_t               vol_id;         /* VOL plugin identigier attached to fapl_id */
-        H5VL_class_t       *vol_cls;        /* VOL class of vol_id */
         va_list             tmp_args;       /* argument list passed from the API call */
         hid_t               fapl_id;
 
@@ -1412,11 +1390,11 @@ H5VL_file_specific(void *file, H5VL_t *vol_plugin, H5VL_file_specific_t specific
         va_end (arguments);
     }
     else {
-        if(NULL == vol_plugin->cls->file_cls.specific)
+        if(NULL == vol_cls->file_cls.specific)
             HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file specific' method")
 
         va_start (arguments, req);
-        if((ret_value = (vol_plugin->cls->file_cls.specific)
+        if((ret_value = (vol_cls->file_cls.specific)
             (file, specific_type, dxpl_id, req, arguments)) < 0)
             HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "specific failed")
         va_end (arguments);
@@ -1441,18 +1419,18 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_file_optional(void *file, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, ...)
+H5VL_file_optional(void *file, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->file_cls.optional)
+    if(NULL == vol_cls->file_cls.optional)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file optional' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->file_cls.optional)(file, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->file_cls.optional)(file, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "optional failed")
     va_end (arguments);
 
@@ -1476,23 +1454,17 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_file_close(void *file, H5VL_t *vol_plugin, hid_t dxpl_id, void **req)
+H5VL_file_close(void *file, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req)
 {
     herr_t              ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->file_cls.close)
+    if(NULL == vol_cls->file_cls.close)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `file close' method")
-    if((ret_value = (vol_plugin->cls->file_cls.close)(file, dxpl_id, req)) < 0)
+    if((ret_value = (vol_cls->file_cls.close)(file, dxpl_id, req)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTCLOSEFILE, FAIL, "close failed")
 
-    vol_plugin->nrefs --;
-    if(H5I_dec_ref(vol_plugin->id) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTDEC, FAIL, "unable to decrement ref count on VOL plugin")
-    if (0 == vol_plugin->nrefs)
-        vol_plugin = (H5VL_t *)H5MM_xfree(vol_plugin);
-
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_file_close() */
@@ -1513,7 +1485,7 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VL_group_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+H5VL_group_create(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, const char *name, 
                   hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, void **req)
 {
     void *ret_value = NULL; /* Return value */
@@ -1521,18 +1493,14 @@ H5VL_group_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, c
     FUNC_ENTER_NOAPI(NULL)
 
     /* check if the corresponding VOL create callback exists */
-    if(NULL == vol_plugin->cls->group_cls.create)
+    if(NULL == vol_cls->group_cls.create)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `group create' method")
 
     /* call the corresponding VOL create callback */
-    if(NULL == (ret_value = (vol_plugin->cls->group_cls.create)
+    if(NULL == (ret_value = (vol_cls->group_cls.create)
                 (obj, loc_params, name, gcpl_id, gapl_id, dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, NULL, "create failed")
 
-    vol_plugin->nrefs ++;
-    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINC, NULL, "unable to increment ref count on VOL plugin")
-
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_group_create() */
@@ -1553,24 +1521,20 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VL_group_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, 
+H5VL_group_open(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, const char *name, 
                 hid_t gapl_id, hid_t dxpl_id, void **req)
 {
     void *ret_value; /* Return value */
 
     FUNC_ENTER_NOAPI(NULL)
 
-    if(NULL == vol_plugin->cls->group_cls.open)
+    if(NULL == vol_cls->group_cls.open)
         HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `group open' method")
 
-    if(NULL == (ret_value = (vol_plugin->cls->group_cls.open)
+    if(NULL == (ret_value = (vol_cls->group_cls.open)
                 (obj, loc_params, name, gapl_id, dxpl_id, req)))
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPENOBJ, NULL, "open failed")
 
-    vol_plugin->nrefs ++;
-    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINC, NULL, "unable to increment ref count on VOL plugin")
-
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_group_open() */
@@ -1591,7 +1555,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_group_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, 
+H5VL_group_get(void *obj, const H5VL_class_t *vol_cls, H5VL_group_get_t get_type, 
                hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
@@ -1599,11 +1563,11 @@ H5VL_group_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type,
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->group_cls.get)
+    if(NULL == vol_cls->group_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `group get' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->group_cls.get)
+    if((ret_value = (vol_cls->group_cls.get)
         (obj, get_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end (arguments);
@@ -1628,7 +1592,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_group_specific(void *obj, H5VL_t *vol_plugin, H5VL_group_specific_t specific_type, 
+H5VL_group_specific(void *obj, const H5VL_class_t *vol_cls, H5VL_group_specific_t specific_type, 
                        hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
@@ -1636,11 +1600,11 @@ H5VL_group_specific(void *obj, H5VL_t *vol_plugin, H5VL_group_specific_t specifi
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->group_cls.specific)
+    if(NULL == vol_cls->group_cls.specific)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `group specific' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->group_cls.specific)
+    if((ret_value = (vol_cls->group_cls.specific)
         (obj, specific_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute group specific callback")
     va_end (arguments);
@@ -1665,18 +1629,18 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_group_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, ...)
+H5VL_group_optional(void *obj, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->group_cls.optional)
+    if(NULL == vol_cls->group_cls.optional)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `group optional' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->group_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->group_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute group optional callback")
     va_end (arguments);
 
@@ -1700,23 +1664,17 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_group_close(void *grp, H5VL_t *vol_plugin, hid_t dxpl_id, void **req)
+H5VL_group_close(void *grp, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req)
 {
     herr_t              ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->group_cls.close)
+    if(NULL == vol_cls->group_cls.close)
         HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `group close' method")
-    if((ret_value = (vol_plugin->cls->group_cls.close)(grp, dxpl_id, req)) < 0)
+    if((ret_value = (vol_cls->group_cls.close)(grp, dxpl_id, req)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "close failed")
 
-    vol_plugin->nrefs --;
-    if(H5I_dec_ref(vol_plugin->id) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTDEC, FAIL, "unable to decrement ref count on VOL plugin")
-    if (0 == vol_plugin->nrefs)
-        vol_plugin = (H5VL_t *)H5MM_xfree(vol_plugin);
-
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_group_close() */
@@ -1736,17 +1694,17 @@ done:
  */
 herr_t
 H5VL_link_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params_t loc_params, 
-                 H5VL_t *vol_plugin, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req)
+                 const H5VL_class_t *vol_cls, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req)
 {
     herr_t               ret_value = SUCCEED;  /* Return value */
 
     FUNC_ENTER_NOAPI(FAIL)
 
     /* check if the corresponding VOL create callback exists */
-    if(NULL == vol_plugin->cls->link_cls.create)
+    if(NULL == vol_cls->link_cls.create)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link create' method")
     /* call the corresponding VOL create callback */
-    if((ret_value = (vol_plugin->cls->link_cls.create)
+    if((ret_value = (vol_cls->link_cls.create)
         (create_type, obj, loc_params, lcpl_id, lapl_id, dxpl_id, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "link create failed")
 
@@ -1769,7 +1727,7 @@ done:
  */
 herr_t 
 H5VL_link_copy(void *src_obj, H5VL_loc_params_t loc_params1, void *dst_obj,
-               H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin,  
+               H5VL_loc_params_t loc_params2, const H5VL_class_t *vol_cls,  
                hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req)
 {
     herr_t               ret_value = SUCCEED;  /* Return value */
@@ -1777,11 +1735,11 @@ H5VL_link_copy(void *src_obj, H5VL_loc_params_t loc_params1, void *dst_obj,
     FUNC_ENTER_NOAPI(FAIL)
 
     /* check if the corresponding VOL copy callback exists */
-    if(NULL == vol_plugin->cls->link_cls.copy)
+    if(NULL == vol_cls->link_cls.copy)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link copy' method")
 
     /* call the corresponding VOL copy callback */
-    if((ret_value = (vol_plugin->cls->link_cls.copy)
+    if((ret_value = (vol_cls->link_cls.copy)
         (src_obj, loc_params1, dst_obj, loc_params2, lcpl_id, 
          lapl_id, dxpl_id, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "link copy failed")
@@ -1805,7 +1763,7 @@ done:
  */
 herr_t 
 H5VL_link_move(void *src_obj, H5VL_loc_params_t loc_params1, void *dst_obj,
-               H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin,  
+               H5VL_loc_params_t loc_params2, const H5VL_class_t *vol_cls,  
                hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req)
 {
     herr_t               ret_value = SUCCEED;  /* Return value */
@@ -1813,11 +1771,11 @@ H5VL_link_move(void *src_obj, H5VL_loc_params_t loc_params1, void *dst_obj,
     FUNC_ENTER_NOAPI(FAIL)
 
     /* check if the corresponding VOL move callback exists */
-    if(NULL == vol_plugin->cls->link_cls.move)
+    if(NULL == vol_cls->link_cls.move)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link move' method")
 
     /* call the corresponding VOL move callback */
-    if((ret_value = (vol_plugin->cls->link_cls.move)
+    if((ret_value = (vol_cls->link_cls.move)
         (src_obj, loc_params1, dst_obj, loc_params2, lcpl_id, 
          lapl_id, dxpl_id, req)) < 0)
 	HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "link move failed")
@@ -1842,7 +1800,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_link_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_link_get_t get_type, 
+H5VL_link_get(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, H5VL_link_get_t get_type, 
               hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
@@ -1850,11 +1808,11 @@ H5VL_link_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->link_cls.get)
+    if(NULL == vol_cls->link_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link get' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->link_cls.get)
+    if((ret_value = (vol_cls->link_cls.get)
         (obj, loc_params, get_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end (arguments);
@@ -1879,7 +1837,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_link_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
+H5VL_link_specific(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, 
                    H5VL_link_specific_t specific_type, hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
@@ -1887,11 +1845,11 @@ H5VL_link_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin,
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->link_cls.specific)
+    if(NULL == vol_cls->link_cls.specific)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link specific' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->link_cls.specific)
+    if((ret_value = (vol_cls->link_cls.specific)
         (obj, loc_params, specific_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute link specific callback")
     va_end (arguments);
@@ -1916,18 +1874,18 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_link_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, ...)
+H5VL_link_optional(void *obj, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->link_cls.optional)
+    if(NULL == vol_cls->link_cls.optional)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `link optional' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->link_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->link_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute link optional callback")
     va_end (arguments);
 
@@ -1951,7 +1909,7 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5VL_object_open(void *obj, H5VL_loc_params_t params, H5VL_t *vol_plugin, H5I_type_t *opened_type,
+H5VL_object_open(void *obj, H5VL_loc_params_t params, const H5VL_class_t *vol_cls, H5I_type_t *opened_type,
                  hid_t dxpl_id, void **req)
 {
     void *ret_value;              /* Return value */
@@ -1959,18 +1917,14 @@ H5VL_object_open(void *obj, H5VL_loc_params_t params, H5VL_t *vol_plugin, H5I_ty
     FUNC_ENTER_NOAPI(NULL)
 
     /* check if the corresponding VOL open callback exists */
-    if(NULL == vol_plugin->cls->object_cls.open)
+    if(NULL == vol_cls->object_cls.open)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, NULL, "vol plugin has no `object open' method")
 
     /* call the corresponding VOL open callback */
-    if(NULL == (ret_value = (vol_plugin->cls->object_cls.open)
+    if(NULL == (ret_value = (vol_cls->object_cls.open)
                 (obj, params, opened_type, dxpl_id, req)))
 	HGOTO_ERROR(H5E_VOL, H5E_CANTOPENOBJ, NULL, "open failed")
 
-    vol_plugin->nrefs++;
-    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINC, NULL, "unable to increment ref count on VOL plugin")
-
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_object_open() */
@@ -1990,8 +1944,8 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t 
-H5VL_object_copy(void *src_obj, H5VL_loc_params_t loc_params1, H5VL_t *vol_plugin1, const char *src_name, 
-                 void *dst_obj, H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin2, const char *dst_name, 
+H5VL_object_copy(void *src_obj, H5VL_loc_params_t loc_params1, const H5VL_class_t *vol_cls1, const char *src_name, 
+                 void *dst_obj, H5VL_loc_params_t loc_params2, const H5VL_class_t *vol_cls2, const char *dst_name, 
                  hid_t ocpypl_id, hid_t lcpl_id, hid_t dxpl_id, void **req)
 {
     herr_t              ret_value = SUCCEED;
@@ -1999,13 +1953,13 @@ H5VL_object_copy(void *src_obj, H5VL_loc_params_t loc_params1, H5VL_t *vol_plugi
     FUNC_ENTER_NOAPI(FAIL)
 
     /* check if both objects are associated with the same VOL plugin */
-    if(vol_plugin1->cls->value != vol_plugin2->cls->value)
+    if(vol_cls1->value != vol_cls2->value)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "Objects are accessed through different VOL plugins and can't be copied")
 
-    if(NULL == vol_plugin1->cls->object_cls.copy)
+    if(NULL == vol_cls1->object_cls.copy)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object copy' method")
 
-    if((ret_value = (vol_plugin1->cls->object_cls.copy)
+    if((ret_value = (vol_cls1->object_cls.copy)
         (src_obj, loc_params1, src_name, dst_obj, loc_params2, dst_name, ocpypl_id, 
          lcpl_id, dxpl_id, req)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "copy failed")
@@ -2030,7 +1984,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_object_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_get_t get_type, 
+H5VL_object_get(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, H5VL_object_get_t get_type, 
                 hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
@@ -2038,11 +1992,11 @@ H5VL_object_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5V
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->object_cls.get)
+    if(NULL == vol_cls->object_cls.get)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object get' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->object_cls.get)
+    if((ret_value = (vol_cls->object_cls.get)
         (obj, loc_params, get_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "get failed")
     va_end (arguments);
@@ -2066,7 +2020,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_object_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, 
+H5VL_object_specific(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, 
                      H5VL_object_specific_t specific_type, hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
@@ -2074,11 +2028,11 @@ H5VL_object_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->object_cls.specific)
+    if(NULL == vol_cls->object_cls.specific)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object specific' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->object_cls.specific)
+    if((ret_value = (vol_cls->object_cls.specific)
         (obj, loc_params, specific_type, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTGET, FAIL, "specific failed")
     va_end (arguments);
@@ -2103,18 +2057,18 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_object_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, ...)
+H5VL_object_optional(void *obj, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req, ...)
 {
     va_list           arguments;             /* argument list passed from the API call */
     herr_t            ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->object_cls.optional)
+    if(NULL == vol_cls->object_cls.optional)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `object optional' method")
 
     va_start (arguments, req);
-    if((ret_value = (vol_plugin->cls->object_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
+    if((ret_value = (vol_cls->object_cls.optional)(obj, dxpl_id, req, arguments)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTOPERATE, FAIL, "Unable to execute object optional callback")
     va_end (arguments);
 
@@ -2137,15 +2091,15 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_request_cancel(void **req, H5VL_t *vol_plugin, H5ES_status_t *status)
+H5VL_request_cancel(void **req, const H5VL_class_t *vol_cls, H5ES_status_t *status)
 {
     herr_t              ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->async_cls.cancel)
+    if(NULL == vol_cls->async_cls.cancel)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `async cancel' method");
-    if((ret_value = (vol_plugin->cls->async_cls.cancel)(req, status)) < 0)
+    if((ret_value = (vol_cls->async_cls.cancel)(req, status)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "request cancel failed")
 
 done:
@@ -2167,15 +2121,15 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_request_test(void **req, H5VL_t *vol_plugin, H5ES_status_t *status)
+H5VL_request_test(void **req, const H5VL_class_t *vol_cls, H5ES_status_t *status)
 {
     herr_t              ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->async_cls.test)
+    if(NULL == vol_cls->async_cls.test)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `async test' method");
-    if((ret_value = (vol_plugin->cls->async_cls.test)(req, status)) < 0)
+    if((ret_value = (vol_cls->async_cls.test)(req, status)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "request test failed")
 
 done:
@@ -2197,15 +2151,15 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VL_request_wait(void **req, H5VL_t *vol_plugin, H5ES_status_t *status)
+H5VL_request_wait(void **req, const H5VL_class_t *vol_cls, H5ES_status_t *status)
 {
     herr_t              ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(FAIL)
 
-    if(NULL == vol_plugin->cls->async_cls.wait)
+    if(NULL == vol_cls->async_cls.wait)
 	HGOTO_ERROR(H5E_VOL, H5E_UNSUPPORTED, FAIL, "vol plugin has no `async wait' method");
-    if((ret_value = (vol_plugin->cls->async_cls.wait)(req, status)) < 0)
+    if((ret_value = (vol_cls->async_cls.wait)(req, status)) < 0)
         HGOTO_ERROR(H5E_VOL, H5E_CANTRELEASE, FAIL, "request wait failed")
 
 done:
diff --git a/src/H5VLnative.c b/src/H5VLnative.c
index 295f146..7277a92 100644
--- a/src/H5VLnative.c
+++ b/src/H5VLnative.c
@@ -244,7 +244,7 @@ H5VL_native_init(void)
     /* Register the Native VOL, if it isn't already */
     if(NULL == H5I_object_verify(H5VL_NATIVE_g, H5I_VOL)) {
         if((H5VL_NATIVE_g = H5VL_register((const H5VL_class_t *)&H5VL_native_g, 
-                                          sizeof(H5VL_class_t), FALSE)) < 0)
+                                          sizeof(H5VL_class_t), TRUE)) < 0)
             HGOTO_ERROR(H5E_ATOM, H5E_CANTINSERT, FAIL, "can't create ID for native plugin")
     }
 
@@ -255,29 +255,6 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_native_init() */
 
-#if 0
-
-/*---------------------------------------------------------------------------
- * Function:    H5VL_native_term
- *
- * Purpose:     Shut down the VOL plugin
- *
- * Returns:     SUCCEED (Can't fail)
- *
- *---------------------------------------------------------------------------
- */
-static herr_t
-H5VL_native_term(void)
-{
-    FUNC_ENTER_NOAPI_NOINIT_NOERR
-
-    /* Reset VFL ID */
-    H5VL_NATIVE_g = 0;
-
-    FUNC_LEAVE_NOAPI(SUCCEED)
-} /* end H5VL_native_term() */
-#endif
-
 
 /*---------------------------------------------------------------------------
  * Function:	H5VL_native_get_file
@@ -388,10 +365,7 @@ H5VL_native_register(H5I_type_t type, void *obj, hbool_t app_ref)
     if(NULL == (vol_plugin = (H5VL_t *)H5MM_calloc(sizeof(H5VL_t))))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
     vol_plugin->cls = &H5VL_native_g;
-    vol_plugin->nrefs = 1;
     vol_plugin->id =  H5VL_NATIVE_g;
-    if(H5I_inc_ref(vol_plugin->id, FALSE) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTINC, FAIL, "unable to increment ref count on VOL plugin")
 
     /* Get an atom for the object */
     if(type == H5I_DATATYPE && ((H5T_t *)obj)->vol_obj == NULL) {
@@ -399,7 +373,7 @@ H5VL_native_register(H5I_type_t type, void *obj, hbool_t app_ref)
             HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to atomize object handle")
     }
     else {
-        if((ret_value = H5I_register2(type, obj, vol_plugin, app_ref)) < 0)
+        if((ret_value = H5VL_register_id(type, obj, vol_plugin, app_ref)) < 0)
             HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to register object")
     }
 
@@ -439,11 +413,9 @@ H5VL_native_unregister(hid_t obj_id)
     if (NULL == (vol_plugin = (H5VL_t *)H5I_get_aux(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain VOL information")
 
-    vol_plugin->nrefs--;
-    if(H5I_dec_ref(vol_plugin->id) < 0)
-        HGOTO_ERROR(H5E_FILE, H5E_CANTDEC, FAIL, "unable to decrement ref count on VOL plugin")
-    if(0 == vol_plugin->nrefs)
-        H5MM_free(vol_plugin);
+    /* decrement ref count on VOL ID */
+    if(H5VL_free_id(vol_plugin) < 0)
+	HGOTO_ERROR(H5E_FILE, H5E_CANTDEC, FAIL, "unable to decrement ref count on VOL plugin")
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
diff --git a/src/H5VLprivate.h b/src/H5VLprivate.h
index 0509a47..1234eb9 100644
--- a/src/H5VLprivate.h
+++ b/src/H5VLprivate.h
@@ -29,9 +29,20 @@
 /****************************/
 /* Library Private Typedefs */
 /****************************/
+
 #define H5_REQUEST_NULL NULL
 #define H5_EVENT_STACK_NULL ((hid_t)-1)
 
+/*
+ * The main datatype for each plugin. 
+ */
+typedef struct H5VL_t {
+    const H5VL_class_t *cls;            /* constant class info */
+    unsigned long       feature_flags;  /* VOL Driver feature Flags */
+    int                 nrefs;          /* number of references by objects using this struct */
+    hid_t               id;             /* identifier for the VOL class */
+} H5VL_t;
+
 /*****************************/
 /* Library Private Variables */
 /*****************************/
@@ -48,70 +59,73 @@ H5_DLL herr_t H5VL_init(void);
 H5_DLL int H5VL_term_interface(void);
 H5_DLL hid_t  H5VL_register(const void *cls, size_t size, hbool_t app_ref);
 H5_DLL hid_t H5VL_object_register(void *obj, H5I_type_t obj_type, H5VL_t *vol_plugin, hbool_t app_ref);
+H5_DLL hid_t H5VL_create_datatype(void *dt_obj, H5VL_t *vol_plugin, hbool_t app_ref);
+H5_DLL hid_t H5VL_register_id(H5I_type_t type, const void *object, H5VL_t *vol_plugin, hbool_t app_ref);
+H5_DLL hid_t H5VL_free_id(H5VL_t *vol_plugin);
 H5_DLL ssize_t H5VL_get_plugin_name(hid_t id, char *name/*out*/, size_t size);
 H5_DLL void *H5VL_get_object(hid_t id);
 
-H5_DLL void *H5VL_attr_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *attr_name, hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, void **req);
-H5_DLL void *H5VL_attr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t aapl_id, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VL_attr_read(void *attr, H5VL_t *vol_plugin, hid_t dtype_id, void *buf, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VL_attr_write(void *attr, H5VL_t *vol_plugin, hid_t dtype_id, const void *buf, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VL_attr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_attr_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_attr_specific_t specific_type, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_attr_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_attr_close(void *attr, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
-
-H5_DLL void *H5VL_dataset_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t dcpl_id, hid_t dapl_id, hid_t dxpl_id, void **req);
-H5_DLL void *H5VL_dataset_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t dapl_id, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VL_dataset_read(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t plist_id, void *buf, void **req);
-H5_DLL herr_t H5VL_dataset_write(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t plist_id, const void *buf, void **req);
-H5_DLL herr_t H5VL_dataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_dataset_specific(void *obj, H5VL_t *vol_plugin, H5VL_dataset_specific_t specific_type, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_dataset_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_dataset_close(void *dset, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
-
-H5_DLL void *H5VL_datatype_commit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t dxpl_id, void **req);
-H5_DLL void *H5VL_datatype_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t tapl_id, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VL_datatype_get(void *dt, H5VL_t *vol_plugin, H5VL_datatype_get_t get_type, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_datatype_specific(void *obj, H5VL_t *vol_plugin, H5VL_datatype_specific_t specific_type, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_datatype_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_datatype_close(void *dt, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
-
-H5_DLL void *H5VL_file_create(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, hid_t dxpl_id, void **req);
-H5_DLL void *H5VL_file_open(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fapl_id, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VL_file_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_file_specific(void *obj, H5VL_t *vol_plugin, H5VL_file_specific_t specific_type, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_file_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_file_close(void *file, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
-
-H5_DLL void *H5VL_group_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, void **req);
-H5_DLL void *H5VL_group_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t gapl_id, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VL_group_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_group_specific(void *obj, H5VL_t *vol_plugin, H5VL_group_specific_t specific_type, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_group_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_group_close(void *grp, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
-
-H5_DLL herr_t H5VL_link_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VL_attr_create(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, const char *attr_name, hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VL_attr_open(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, const char *name, hid_t aapl_id, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VL_attr_read(void *attr, const H5VL_class_t *vol_cls, hid_t dtype_id, void *buf, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VL_attr_write(void *attr, const H5VL_class_t *vol_cls, hid_t dtype_id, const void *buf, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VL_attr_get(void *obj, const H5VL_class_t *vol_cls, H5VL_attr_get_t get_type, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_attr_specific(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, H5VL_attr_specific_t specific_type, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_attr_optional(void *obj, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_attr_close(void *attr, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req);
+
+H5_DLL void *H5VL_dataset_create(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, const char *name, hid_t dcpl_id, hid_t dapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VL_dataset_open(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, const char *name, hid_t dapl_id, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VL_dataset_read(void *dset, const H5VL_class_t *vol_cls, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t plist_id, void *buf, void **req);
+H5_DLL herr_t H5VL_dataset_write(void *dset, const H5VL_class_t *vol_cls, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t plist_id, const void *buf, void **req);
+H5_DLL herr_t H5VL_dataset_get(void *dset, const H5VL_class_t *vol_cls, H5VL_dataset_get_t get_type, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_dataset_specific(void *obj, const H5VL_class_t *vol_cls, H5VL_dataset_specific_t specific_type, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_dataset_optional(void *obj, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_dataset_close(void *dset, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req);
+
+H5_DLL void *H5VL_datatype_commit(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, const char *name, hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VL_datatype_open(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, const char *name, hid_t tapl_id, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VL_datatype_get(void *dt, const H5VL_class_t *vol_cls, H5VL_datatype_get_t get_type, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_datatype_specific(void *obj, const H5VL_class_t *vol_cls, H5VL_datatype_specific_t specific_type, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_datatype_optional(void *obj, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_datatype_close(void *dt, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req);
+
+H5_DLL void *H5VL_file_create(const H5VL_class_t *vol_cls, const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VL_file_open(const H5VL_class_t *vol_cls, const char *name, unsigned flags, hid_t fapl_id, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VL_file_get(void *file, const H5VL_class_t *vol_cls, H5VL_file_get_t get_type, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_file_specific(void *obj, const H5VL_class_t *vol_cls, H5VL_file_specific_t specific_type, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_file_optional(void *obj, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_file_close(void *file, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req);
+
+H5_DLL void *H5VL_group_create(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, const char *name, hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VL_group_open(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, const char *name, hid_t gapl_id, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VL_group_get(void *obj, const H5VL_class_t *vol_cls, H5VL_group_get_t get_type, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_group_specific(void *obj, const H5VL_class_t *vol_cls, H5VL_group_specific_t specific_type, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_group_optional(void *obj, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_group_close(void *grp, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req);
+
+H5_DLL herr_t H5VL_link_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req);
 H5_DLL herr_t H5VL_link_copy(void *src_obj, H5VL_loc_params_t loc_params1,
-                             void *dst_obj, H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin,
+                             void *dst_obj, H5VL_loc_params_t loc_params2, const H5VL_class_t *vol_cls,
                              hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req);
 H5_DLL herr_t H5VL_link_move(void *src_obj, H5VL_loc_params_t loc_params1,
-                             void *dst_obj, H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin,
+                             void *dst_obj, H5VL_loc_params_t loc_params2, const H5VL_class_t *vol_cls,
                              hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VL_link_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_link_get_t get_type, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_link_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_link_specific_t specific_type, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_link_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_link_get(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, H5VL_link_get_t get_type, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_link_specific(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, H5VL_link_specific_t specific_type, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_link_optional(void *obj, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req, ...);
 
-H5_DLL void *H5VL_object_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5I_type_t *opened_type, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VL_object_copy(void *src_obj, H5VL_loc_params_t loc_params1, H5VL_t *vol_plugin1, const char *src_name, 
-                               void *dst_obj, H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin2, const char *dst_name, 
+H5_DLL void *H5VL_object_open(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, H5I_type_t *opened_type, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VL_object_copy(void *src_obj, H5VL_loc_params_t loc_params1, const H5VL_class_t *vol_cls1, const char *src_name, 
+                               void *dst_obj, H5VL_loc_params_t loc_params2, const H5VL_class_t *vol_cls2, const char *dst_name, 
                                hid_t ocpypl_id, hid_t lcpl_id, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VL_object_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_get_t get_type, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_object_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_specific_t specific_type, hid_t dxpl_id, void **req, ...);
-H5_DLL herr_t H5VL_object_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_object_get(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, H5VL_object_get_t get_type, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_object_specific(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *vol_cls, H5VL_object_specific_t specific_type, hid_t dxpl_id, void **req, ...);
+H5_DLL herr_t H5VL_object_optional(void *obj, const H5VL_class_t *vol_cls, hid_t dxpl_id, void **req, ...);
 
-H5_DLL herr_t H5VL_request_cancel(void **req, H5VL_t *vol_plugin, H5ES_status_t *status);
-H5_DLL herr_t H5VL_request_test(void **req, H5VL_t *vol_plugin, H5ES_status_t *status);
-H5_DLL herr_t H5VL_request_wait(void **req, H5VL_t *vol_plugin, H5ES_status_t *status);
+H5_DLL herr_t H5VL_request_cancel(void **req, const H5VL_class_t *vol_cls, H5ES_status_t *status);
+H5_DLL herr_t H5VL_request_test(void **req, const H5VL_class_t *vol_cls, H5ES_status_t *status);
+H5_DLL herr_t H5VL_request_wait(void **req, const H5VL_class_t *vol_cls, H5ES_status_t *status);
 
 H5_DLL herr_t H5VL_fapl_open(struct H5P_genplist_t *plist, hid_t vol_id, const void *vol_info);
 H5_DLL herr_t H5VL_fapl_copy(hid_t vol_id, const void *vol_info, void **copied_info);
diff --git a/src/H5VLpublic.h b/src/H5VLpublic.h
index f81ca1d..c3face6 100644
--- a/src/H5VLpublic.h
+++ b/src/H5VLpublic.h
@@ -347,95 +347,83 @@ typedef struct H5VL_class_t {
     herr_t (*optional)(void *obj, hid_t dxpl_id, void **req, va_list arguments);
 } H5VL_class_t;
 
-/*
- * The main datatype for each plugin. Public fields common to all
- * plugins are declared here and the plugin appends private fields in
- * memory.
- */
-typedef struct H5VL_t {
-    const H5VL_class_t *cls;            /* constant class info */
-    unsigned long       feature_flags;  /* VOL Driver feature Flags */
-    int                 nrefs;          /* number of references by objects using this struct */
-    hid_t               id;             /* identifier for the VOL class */
-} H5VL_t;
-
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-H5_DLL void *H5VLattr_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *attr_name, hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, void **req);
-H5_DLL void *H5VLattr_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t aapl_id, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VLattr_read(void *attr, H5VL_t *vol_plugin, hid_t dtype_id, void *buf, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VLattr_write(void *attr, H5VL_t *vol_plugin, hid_t dtype_id, const void *buf, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VLattr_get(void *obj, H5VL_t *vol_plugin, H5VL_attr_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLattr_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_attr_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLattr_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLattr_close(void *attr, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
-
-H5_DLL void *H5VLdataset_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t dcpl_id, hid_t dapl_id, hid_t dxpl_id, void **req);
-H5_DLL void *H5VLdataset_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t dapl_id, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VLdataset_read(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t plist_id, void *buf, void **req);
-H5_DLL herr_t H5VLdataset_write(void *dset, H5VL_t *vol_plugin, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t plist_id, const void *buf, void **req);
-H5_DLL herr_t H5VLdataset_get(void *dset, H5VL_t *vol_plugin, H5VL_dataset_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLdataset_specific(void *obj, H5VL_t *vol_plugin, H5VL_dataset_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLdataset_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLdataset_close(void *dset, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
-
-H5_DLL void *H5VLdatatype_commit(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t dxpl_id, void **req);
-H5_DLL void *H5VLdatatype_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t tapl_id, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VLdatatype_get(void *dt, H5VL_t *vol_plugin, H5VL_datatype_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLdatatype_specific(void *obj, H5VL_t *vol_plugin, H5VL_datatype_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLdatatype_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLdatatype_close(void *dt, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
-
-H5_DLL void *H5VLfile_create(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, hid_t dxpl_id, void **req);
-H5_DLL void *H5VLfile_open(H5VL_t **vol_plugin, const char *name, unsigned flags, hid_t fapl_id, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VLfile_get(void *file, H5VL_t *vol_plugin, H5VL_file_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLfile_specific(void *obj, H5VL_t *vol_plugin, H5VL_file_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLfile_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLfile_close(void *file, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
-
-H5_DLL void *H5VLgroup_create(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, void **req);
-H5_DLL void *H5VLgroup_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, const char *name, hid_t gapl_id, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VLgroup_get(void *obj, H5VL_t *vol_plugin, H5VL_group_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLgroup_specific(void *obj, H5VL_t *vol_plugin, H5VL_group_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLgroup_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLgroup_close(void *grp, H5VL_t *vol_plugin, hid_t dxpl_id, void **req);
-
-H5_DLL herr_t H5VLlink_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VLattr_create(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, const char *attr_name, hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VLattr_open(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, const char *name, hid_t aapl_id, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLattr_read(void *attr, hid_t plugin_id, hid_t dtype_id, void *buf, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLattr_write(void *attr, hid_t plugin_id, hid_t dtype_id, const void *buf, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLattr_get(void *obj, hid_t plugin_id, H5VL_attr_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLattr_specific(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, H5VL_attr_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLattr_optional(void *obj, hid_t plugin_id, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLattr_close(void *attr, hid_t plugin_id, hid_t dxpl_id, void **req);
+
+H5_DLL void *H5VLdataset_create(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, const char *name, hid_t dcpl_id, hid_t dapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VLdataset_open(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, const char *name, hid_t dapl_id, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLdataset_read(void *dset, hid_t plugin_id, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t plist_id, void *buf, void **req);
+H5_DLL herr_t H5VLdataset_write(void *dset, hid_t plugin_id, hid_t mem_type_id, hid_t mem_space_id, hid_t file_space_id, hid_t plist_id, const void *buf, void **req);
+H5_DLL herr_t H5VLdataset_get(void *dset, hid_t plugin_id, H5VL_dataset_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLdataset_specific(void *obj, hid_t plugin_id, H5VL_dataset_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLdataset_optional(void *obj, hid_t plugin_id, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLdataset_close(void *dset, hid_t plugin_id, hid_t dxpl_id, void **req);
+
+H5_DLL void *H5VLdatatype_commit(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, const char *name, hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, hid_t tapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VLdatatype_open(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, const char *name, hid_t tapl_id, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLdatatype_get(void *dt, hid_t plugin_id, H5VL_datatype_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLdatatype_specific(void *obj, hid_t plugin_id, H5VL_datatype_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLdatatype_optional(void *obj, hid_t plugin_id, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLdatatype_close(void *dt, hid_t plugin_id, hid_t dxpl_id, void **req);
+
+H5_DLL void *H5VLfile_create(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VLfile_open(const char *name, unsigned flags, hid_t fapl_id, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLfile_get(void *file, hid_t plugin_id, H5VL_file_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLfile_specific(void *obj, hid_t plugin_id, H5VL_file_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLfile_optional(void *obj, hid_t plugin_id, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLfile_close(void *file, hid_t plugin_id, hid_t dxpl_id, void **req);
+
+H5_DLL void *H5VLgroup_create(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, const char *name, hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, void **req);
+H5_DLL void *H5VLgroup_open(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, const char *name, hid_t gapl_id, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLgroup_get(void *obj, hid_t plugin_id, H5VL_group_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLgroup_specific(void *obj, hid_t plugin_id, H5VL_group_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLgroup_optional(void *obj, hid_t plugin_id, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLgroup_close(void *grp, hid_t plugin_id, hid_t dxpl_id, void **req);
+
+H5_DLL herr_t H5VLlink_create(H5VL_link_create_type_t create_type, void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req);
 H5_DLL herr_t H5VLlink_copy(void *src_obj, H5VL_loc_params_t loc_params1,
-                             void *dst_obj, H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin,
+                             void *dst_obj, H5VL_loc_params_t loc_params2, hid_t plugin_id,
                              hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req);
 H5_DLL herr_t H5VLlink_move(void *src_obj, H5VL_loc_params_t loc_params1,
-                             void *dst_obj, H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin,
+                             void *dst_obj, H5VL_loc_params_t loc_params2, hid_t plugin_id,
                              hid_t lcpl_id, hid_t lapl_id, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VLlink_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_link_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLlink_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_link_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLlink_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLlink_get(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, H5VL_link_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLlink_specific(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, H5VL_link_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLlink_optional(void *obj, hid_t plugin_id, hid_t dxpl_id, void **req, va_list arguments);
 
-H5_DLL void *H5VLobject_open(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5I_type_t *opened_type, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VLobject_copy(void *src_obj, H5VL_loc_params_t loc_params1, H5VL_t *vol_plugin1, const char *src_name, 
-                               void *dst_obj, H5VL_loc_params_t loc_params2, H5VL_t *vol_plugin2, const char *dst_name, 
+H5_DLL void *H5VLobject_open(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, H5I_type_t *opened_type, hid_t dxpl_id, void **req);
+H5_DLL herr_t H5VLobject_copy(void *src_obj, H5VL_loc_params_t loc_params1, hid_t plugin_id1, const char *src_name, 
+                               void *dst_obj, H5VL_loc_params_t loc_params2, hid_t plugin_id2, const char *dst_name, 
                                hid_t ocpypl_id, hid_t lcpl_id, hid_t dxpl_id, void **req);
-H5_DLL herr_t H5VLobject_get(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLobject_specific(void *obj, H5VL_loc_params_t loc_params, H5VL_t *vol_plugin, H5VL_object_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments);
-H5_DLL herr_t H5VLobject_optional(void *obj, H5VL_t *vol_plugin, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLobject_get(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, H5VL_object_get_t get_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLobject_specific(void *obj, H5VL_loc_params_t loc_params, hid_t plugin_id, H5VL_object_specific_t specific_type, hid_t dxpl_id, void **req, va_list arguments);
+H5_DLL herr_t H5VLobject_optional(void *obj, hid_t plugin_id, hid_t dxpl_id, void **req, va_list arguments);
 
-H5_DLL herr_t H5VLrequest_cancel(void **req, H5VL_t *vol_plugin, H5ES_status_t *status);
-H5_DLL herr_t H5VLrequest_test(void **req, H5VL_t *vol_plugin, H5ES_status_t *status);
-H5_DLL herr_t H5VLrequest_wait(void **req, H5VL_t *vol_plugin, H5ES_status_t *status);
+H5_DLL herr_t H5VLrequest_cancel(void **req, hid_t plugin_id, H5ES_status_t *status);
+H5_DLL herr_t H5VLrequest_test(void **req, hid_t plugin_id, H5ES_status_t *status);
+H5_DLL herr_t H5VLrequest_wait(void **req, hid_t plugin_id, H5ES_status_t *status);
 
 /* Function prototypes */
 H5_DLL herr_t H5VLinitialize(hid_t plugin_id, hid_t vipl_id);
 H5_DLL herr_t H5VLterminate(hid_t plugin_id, hid_t vtpl_id);
-H5_DLL hid_t H5VLget_plugin_id(const H5VL_class_t *cls);
+H5_DLL hid_t H5VLget_plugin_id(const char *name);
 H5_DLL herr_t H5VLclose(hid_t plugin_id);
 H5_DLL hid_t H5VLregister(const H5VL_class_t *cls);
 H5_DLL herr_t H5VLunregister(hid_t plugin_id);
-H5_DLL htri_t H5VLis_registered(const H5VL_class_t *cls);
+H5_DLL htri_t H5VLis_registered(const char *name);
 H5_DLL ssize_t H5VLget_plugin_name(hid_t id, char *name/*out*/, size_t size);
-H5_DLL hid_t H5VLobject_register(void *obj, H5I_type_t obj_type, const H5VL_class_t *cls);
-H5_DLL herr_t H5VLget_object(hid_t obj_id, void **obj, H5VL_t **vol_plugin);
+H5_DLL hid_t H5VLobject_register(void *obj, H5I_type_t obj_type, hid_t plugin_id);
+H5_DLL herr_t H5VLget_object(hid_t obj_id, void **obj);
 #if 0
 H5_DLL hid_t H5VLregister_by_name(const char *plugin_name);
 H5_DLL herr_t H5VLioctl(hid_t loc_id or vol_id, <class enum>, ...);
diff --git a/tools/misc/repart_test.c b/tools/misc/repart_test.c
index e6da779..e718ee1 100644
--- a/tools/misc/repart_test.c
+++ b/tools/misc/repart_test.c
@@ -87,6 +87,7 @@ test_family_h5repart_opens(void)
 error:
     H5E_BEGIN_TRY {
         H5Fclose(file);
+        H5Pclose(fapl);
     } H5E_END_TRY;
     return -1;
 }