[svn-r21442] Description:

    Check in "actual I/O mode" feature to trunk.  Will merge back to 1.8 branch
after it bakes over the weekend.

Tested on:
    FreeBSD/32 8.2 (loyalty) w/gcc4.6, w/C++ & FORTRAN, in debug mode
    FreeBSD/64 8.2 (freedom) w/gcc4.6, w/C++ & FORTRAN, in debug mode
    Linux/32 2.6 (jam) w/PGI compilers, w/default API=1.8.x,
        w/C++ & FORTRAN, w/threadsafe, in debug mode
    Linux/64-amd64 2.6 (koala) w/Intel compilers, w/default API=1.6.x,
        w/C++ & FORTRAN, in production mode
    Solaris/32 2.10 (linew) w/deprecated symbols disabled, w/C++ & FORTRAN,
        w/szip filter, w/threadsafe, in production mode
    Linux/PPC 2.6 (heiwa) w/C++ & FORTRAN, w/threadsafe, in debug mode
    Linux/64-ia64 2.6 (ember) w/Intel compilers, w/C++ & FORTRAN,
        in production mode
    Linux/64-amd64 2.6 (abe) w/parallel, w/FORTRAN, in debug mode
    Mac OS X/32 10.6.8 (amazon) in debug mode
    Mac OS X/32 10.6.8 (amazon) w/C++ & FORTRAN, w/threadsafe,
        in production mode

6 files changed, 228 insertions, 15 deletions

diff --git a/src/H5Dio.c b/src/H5Dio.c
index 7ee304c..7268b25 100644
--- a/src/H5Dio.c
+++ b/src/H5Dio.c
@@ -340,7 +340,7 @@ H5D_read(H5D_t *dataset, hid_t mem_type_id, const H5S_t *mem_space,
 #ifdef H5_HAVE_PARALLEL
     /* Collective access is not permissible without a MPI based VFD */
     if(dxpl_cache->xfer_mode == H5FD_MPIO_COLLECTIVE && 
-      !(H5F_HAS_FEATURE(dataset->oloc.file, H5FD_FEAT_HAS_MPI)))
+            !(H5F_HAS_FEATURE(dataset->oloc.file, H5FD_FEAT_HAS_MPI)))
         HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL, "collective access for MPI-based drivers only")
 #endif /*H5_HAVE_PARALLEL*/
 
@@ -603,7 +603,7 @@ H5D_write(H5D_t *dataset, hid_t mem_type_id, const H5S_t *mem_space,
             HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to construct projected memory dataspace")
         HDassert(projected_mem_space);
         HDassert(adj_buf);
-            
+
         /* Switch to using projected memory dataspace & adjusted buffer */
         mem_space = projected_mem_space;
         buf = adj_buf;
@@ -950,6 +950,9 @@ H5D_ioinfo_adjust(H5D_io_info_t *io_info, const H5D_t *dset, hid_t dxpl_id,
     const H5S_t *file_space, const H5S_t *mem_space,
     const H5D_type_info_t *type_info, const H5D_chunk_map_t *fm)
 {
+    H5P_genplist_t *dx_plist;       /* Data transer property list */
+    H5D_mpio_actual_chunk_opt_mode_t actual_chunk_opt_mode; /* performed chunk optimization */
+    H5D_mpio_actual_io_mode_t actual_io_mode; /* performed io mode */
     herr_t	ret_value = SUCCEED;	/* Return value	*/
 
     FUNC_ENTER_NOAPI_NOINIT(H5D_ioinfo_adjust)
@@ -963,6 +966,20 @@ H5D_ioinfo_adjust(H5D_io_info_t *io_info, const H5D_t *dset, hid_t dxpl_id,
     HDassert(type_info->tpath);
     HDassert(io_info);
 
+    /* Get the dataset transfer property list */
+    if(NULL == (dx_plist = (H5P_genplist_t *)H5I_object(dxpl_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset transfer property list")
+
+    /* Reset the actual io mode properties to the default values in case
+     * the dxpl was previously used in a collective I/O operation.
+     */
+    actual_chunk_opt_mode = H5D_MPIO_NO_CHUNK_OPTIMIZATION;
+    actual_io_mode = H5D_MPIO_NO_COLLECTIVE;
+    if(H5P_set(dx_plist, H5D_MPIO_ACTUAL_CHUNK_OPT_MODE_NAME, &actual_chunk_opt_mode) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "couldn't set actual chunk opt mode property")
+    if(H5P_set(dx_plist, H5D_MPIO_ACTUAL_IO_MODE_NAME, &actual_io_mode) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "couldn't set actual io mode property")
+
     /* Make any parallel I/O adjustments */
     if(io_info->using_mpi_vfd) {
         htri_t opt;         /* Flag whether a selection is optimizable */
@@ -995,12 +1012,6 @@ H5D_ioinfo_adjust(H5D_io_info_t *io_info, const H5D_t *dset, hid_t dxpl_id,
              * mark it so that we remember to revert the change.
              */
             if(io_info->dxpl_cache->xfer_mode == H5FD_MPIO_COLLECTIVE) {
-                H5P_genplist_t *dx_plist;           /* Data transer property list */
-
-                /* Get the dataset transfer property list */
-                if(NULL == (dx_plist = (H5P_genplist_t *)H5I_object(dxpl_id)))
-                    HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset creation property list")
-
                 /* Change the xfer_mode to independent for handling the I/O */
                 io_info->dxpl_cache->xfer_mode = H5FD_MPIO_INDEPENDENT;
                 if(H5P_set(dx_plist, H5D_XFER_IO_XFER_MODE_NAME, &io_info->dxpl_cache->xfer_mode) < 0)
diff --git a/src/H5Dmpio.c b/src/H5Dmpio.c
index 1c69305..8c78af2 100644
--- a/src/H5Dmpio.c
+++ b/src/H5Dmpio.c
@@ -471,6 +471,8 @@ H5D_contig_collective_read(H5D_io_info_t *io_info, const H5D_type_info_t *type_i
     hsize_t UNUSED nelmts, const H5S_t *file_space, const H5S_t *mem_space,
     H5D_chunk_map_t UNUSED *fm)
 {
+    H5D_mpio_actual_io_mode_t actual_io_mode = H5D_MPIO_CONTIGUOUS_COLLECTIVE;
+    H5P_genplist_t *dx_plist;           /* Pointer to DXPL */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI(H5D_contig_collective_read, FAIL)
@@ -483,6 +485,16 @@ H5D_contig_collective_read(H5D_io_info_t *io_info, const H5D_type_info_t *type_i
     if(H5D_inter_collective_io(io_info, type_info, file_space, mem_space) < 0)
         HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "couldn't finish shared collective MPI-IO")
 
+    /* Obtain the data transfer properties */
+    if(NULL == (dx_plist = H5I_object(io_info->dxpl_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data transfer property list")
+
+    /* Set the actual I/O mode property. internal_collective_io will not break to
+     * independent I/O, so we set it here.
+     */
+    if(H5P_set(dx_plist, H5D_MPIO_ACTUAL_IO_MODE_NAME, &actual_io_mode) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "couldn't set actual io mode property")
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5D_contig_collective_read() */
@@ -506,6 +518,8 @@ H5D_contig_collective_write(H5D_io_info_t *io_info, const H5D_type_info_t *type_
     hsize_t UNUSED nelmts, const H5S_t *file_space, const H5S_t *mem_space,
     H5D_chunk_map_t UNUSED *fm)
 {
+    H5D_mpio_actual_io_mode_t actual_io_mode = H5D_MPIO_CONTIGUOUS_COLLECTIVE;
+    H5P_genplist_t *dx_plist;           /* Pointer to DXPL */
     herr_t ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI(H5D_contig_collective_write, FAIL)
@@ -518,6 +532,16 @@ H5D_contig_collective_write(H5D_io_info_t *io_info, const H5D_type_info_t *type_
     if(H5D_inter_collective_io(io_info, type_info, file_space, mem_space) < 0)
         HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "couldn't finish shared collective MPI-IO")
 
+    /* Obtain the data transfer properties */
+    if(NULL == (dx_plist = H5I_object(io_info->dxpl_id)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data transfer property list")
+
+    /* Set the actual I/O mode property. internal_collective_io will not break to
+     * independent I/O, so we set it here.
+     */
+    if(H5P_set(dx_plist, H5D_MPIO_ACTUAL_IO_MODE_NAME, &actual_io_mode) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "couldn't set actual io mode property")
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5D_contig_collective_write() */
@@ -559,6 +583,8 @@ H5D_chunk_collective_io(H5D_io_info_t *io_info, const H5D_type_info_t *type_info
 {
     H5P_genplist_t *dx_plist;           /* Pointer to DXPL */
     H5FD_mpio_chunk_opt_t chunk_opt_mode;
+    H5D_mpio_actual_chunk_opt_mode_t actual_chunk_opt_mode;
+    H5D_mpio_actual_io_mode_t actual_io_mode;
     int         io_option = H5D_MULTI_CHUNK_IO_MORE_OPT;
     int         sum_chunk = -1;
 #ifdef H5_HAVE_INSTRUMENTED_LIBRARY
@@ -646,15 +672,38 @@ H5D_chunk_collective_io(H5D_io_info_t *io_info, const H5D_type_info_t *type_info
 
     /* step 2:  Go ahead to do IO.*/
     if(io_option == H5D_ONE_LINK_CHUNK_IO || io_option == H5D_ONE_LINK_CHUNK_IO_MORE_OPT) {
+        /* set the actual io mode properties to the correct values for link chunk io.
+         * Link chunk I/O does not break to independent, so we can set the actual_io mode
+         * as well as the optimisation mode. */
+        actual_chunk_opt_mode = H5D_MPIO_LINK_CHUNK;
+        actual_io_mode = H5D_MPIO_CHUNK_COLLECTIVE;
+
+        /* Set the actual chunk opt mode property. */
+        if(H5P_set(dx_plist, H5D_MPIO_ACTUAL_CHUNK_OPT_MODE_NAME, &actual_chunk_opt_mode) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "couldn't set actual chunk opt mode property")
+
         if(H5D_link_chunk_collective_io(io_info, type_info, fm, sum_chunk) < 0)
             HGOTO_ERROR(H5E_IO, H5E_CANTGET, FAIL, "couldn't finish linked chunk MPI-IO")
+
+        /* Set the actual io mode property. */
+        if(H5P_set(dx_plist, H5D_MPIO_ACTUAL_IO_MODE_NAME, &actual_io_mode) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "couldn't set actual io mode property")
     } /* end if */
     else
     if(io_option == H5D_MULTI_CHUNK_IO) {
+        /* Set the actual chunk opt mode property */
+        actual_chunk_opt_mode = H5D_MPIO_MULTI_CHUNK_NO_OPT;
+        if(H5P_set(dx_plist, H5D_MPIO_ACTUAL_CHUNK_OPT_MODE_NAME, &actual_chunk_opt_mode) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "couldn't set actual chunk opt mode property")
+
         if(H5D_multi_chunk_collective_io_no_opt(io_info, type_info, fm, dx_plist) < 0)
             HGOTO_ERROR(H5E_IO, H5E_CANTGET, FAIL, "couldn't finish multiple chunk MPI-IO")
     } /* end if */
     else { /*multiple chunk IOs with opt */
+        actual_chunk_opt_mode = H5D_MPIO_MULTI_CHUNK;
+        if(H5P_set(dx_plist, H5D_MPIO_ACTUAL_CHUNK_OPT_MODE_NAME, &actual_chunk_opt_mode) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "couldn't set actual chunk opt mode property")
+
         if(H5D_multi_chunk_collective_io(io_info, type_info, fm, dx_plist) < 0)
             HGOTO_ERROR(H5E_IO, H5E_CANTGET, FAIL, "couldn't finish optimized multiple chunk MPI-IO")
     } /* end else */
@@ -1036,6 +1085,7 @@ H5D_multi_chunk_collective_io(H5D_io_info_t *io_info, const H5D_type_info_t *typ
     int mpi_rank;
 #endif
     size_t              u;                    /* Local index variable */
+    H5D_mpio_actual_io_mode_t actual_io_mode = H5D_MPIO_NO_COLLECTIVE; /* Local variable for tracking the I/O mode used. */
     herr_t              ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI_NOINIT(H5D_multi_chunk_collective_io)
@@ -1115,6 +1165,15 @@ if(H5DEBUG(D))
             if(chunk_info) {
                 fspace = chunk_info->fspace;
                 mspace = chunk_info->mspace;
+
+                /* Update the local variable tracking the dxpl's actual io mode property.
+                 *
+                 * Note: H5D_MPIO_COLLECTIVE_MULTI | H5D_MPIO_INDEPENDENT = H5D_MPIO_MIXED
+                 *      to ease switching between to mixed I/O without checking the current
+                 *      value of the property. You can see the definition in H5Ppublic.h
+                 */
+                actual_io_mode = actual_io_mode | H5D_MPIO_CHUNK_COLLECTIVE;
+
             } /* end if */
             else {
                 fspace = mspace = NULL;
@@ -1151,6 +1210,9 @@ if(H5DEBUG(D))
             if(chunk_info) {
                 fspace = chunk_info->fspace;
                 mspace = chunk_info->mspace;
+
+                /* Update the local variable tracking the dxpl's actual io mode. */
+                actual_io_mode = actual_io_mode | H5D_MPIO_CHUNK_INDEPENDENT;
             } /* end if */
             else {
                 fspace = mspace = NULL;
@@ -1176,6 +1238,10 @@ if(H5DEBUG(D))
         } /* end else */
     } /* end for */
 
+    /* Write the local value of actual io mode to the DXPL. */
+    if(H5P_set(dx_plist, H5D_MPIO_ACTUAL_IO_MODE_NAME, &actual_io_mode) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "couldn't set actual io mode property")
+
 done:
     if(chunk_io_option)
         H5MM_xfree(chunk_io_option);
@@ -1226,6 +1292,7 @@ H5D_multi_chunk_collective_io_no_opt(H5D_io_info_t *io_info,
     int             min_chunk = -1;       /* Minimum # of chunks all processes will operate on */
     int             count_chunk;          /* How many chunks have we operated on? */
     H5D_storage_t   store;                /* union of EFL and chunk pointer in file space */
+    H5D_mpio_actual_io_mode_t actual_io_mode = H5D_MPIO_NO_COLLECTIVE; /*Local variable for tracking the I/O modes used. */
     herr_t          ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI_NOINIT(H5D_multi_chunk_collective_io_no_opt)
@@ -1308,6 +1375,9 @@ if(H5DEBUG(D)) {
             if(H5D_ioinfo_xfer_mode(io_info, dx_plist, H5FD_MPIO_INDEPENDENT) < 0)
                 HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't switch to independent I/O")
 
+            /* Update the local variable tracking the dxpl's actual io mode */
+            actual_io_mode = actual_io_mode | H5D_MPIO_CHUNK_INDEPENDENT;
+
             /* Load the chunk into cache and lock it. */
             if((cacheable = H5D_chunk_cacheable(io_info, udata.addr,
                     io_info->op_type == H5D_IO_OP_WRITE)) < 0)
@@ -1364,6 +1434,9 @@ if(H5DEBUG(D)) {
             /* Set up the storage address information for this chunk */
             ctg_store.contig.dset_addr = udata.addr;
 
+            /* Update the local variable tracking the dxpl's actual io Mode. */
+            actual_io_mode = actual_io_mode | H5D_MPIO_CHUNK_COLLECTIVE;
+
             if(H5D_inter_collective_io(&ctg_io_info, type_info, chunk_info->fspace, chunk_info->mspace) < 0)
                 HGOTO_ERROR(H5E_IO, H5E_CANTGET, FAIL,"couldn't finish shared collective MPI-IO")
         } /* end else */
@@ -1376,6 +1449,10 @@ if(H5DEBUG(D)) {
         chunk_node = H5SL_next(chunk_node);
     } /* end while */
 
+    /* Write the local value of actual io mode to the DXPL. */
+    if(H5P_set(dx_plist, H5D_MPIO_ACTUAL_IO_MODE_NAME, &actual_io_mode) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "couldn't set actual io mode property")
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5D_multi_chunk_collective_io_no_opt */
diff --git a/src/H5Dprivate.h b/src/H5Dprivate.h
index cc770df..a4dddf5 100644
--- a/src/H5Dprivate.h
+++ b/src/H5Dprivate.h
@@ -72,6 +72,8 @@
 #define H5D_XFER_MPIO_CHUNK_OPT_HARD_NAME "mpio_chunk_opt_hard"
 #define H5D_XFER_MPIO_CHUNK_OPT_NUM_NAME "mpio_chunk_opt_num"
 #define H5D_XFER_MPIO_CHUNK_OPT_RATIO_NAME "mpio_chunk_opt_ratio"
+#define H5D_MPIO_ACTUAL_CHUNK_OPT_MODE_NAME "actual_chunk_opt_mode"
+#define H5D_MPIO_ACTUAL_IO_MODE_NAME    "actual_io_mode"
 #endif /* H5_HAVE_PARALLEL */
 #define H5D_XFER_EDC_NAME               "err_detect"    /* EDC */
 #define H5D_XFER_FILTER_CB_NAME         "filter_cb"     /* Filter callback function */
diff --git a/src/H5Fsuper_cache.c b/src/H5Fsuper_cache.c
index 56f9219..cb4ee0e 100644
--- a/src/H5Fsuper_cache.c
+++ b/src/H5Fsuper_cache.c
@@ -469,7 +469,7 @@ H5F_sblock_load(H5F_t *f, hid_t dxpl_id, haddr_t UNUSED addr, void *_udata)
 
     /* (Account for the stored EOA being absolute offset -QAK) */
     if((eof + sblock->base_addr) < stored_eoa)
-        HGOTO_ERROR(H5E_FILE, H5E_TRUNCATED, NULL, "truncated file")
+        HGOTO_ERROR(H5E_FILE, H5E_TRUNCATED, NULL, "truncated file: eof = %llu, sblock->base_addr = %llu, stored_eoa = %llu", (unsigned long long)eof, (unsigned long long)sblock->base_addr, (unsigned long long)stored_eoa)
 
     /*
      * Tell the file driver how much address space has already been
diff --git a/src/H5Pdxpl.c b/src/H5Pdxpl.c
index 8530b8b..3408ced 100644
--- a/src/H5Pdxpl.c
+++ b/src/H5Pdxpl.c
@@ -98,14 +98,20 @@
 #define H5D_XFER_MPIO_CHUNK_OPT_HARD_DEF        H5FD_MPIO_CHUNK_DEFAULT
 #define H5D_XFER_MPIO_CHUNK_OPT_NUM_SIZE        sizeof(unsigned)
 #define H5D_XFER_MPIO_CHUNK_OPT_NUM_DEF         H5D_ONE_LINK_CHUNK_IO_THRESHOLD
-#define H5D_XFER_MPIO_CHUNK_OPT_RATIO_SIZE       sizeof(unsigned)
+#define H5D_XFER_MPIO_CHUNK_OPT_RATIO_SIZE      sizeof(unsigned)
 #define H5D_XFER_MPIO_CHUNK_OPT_RATIO_DEF       H5D_MULTI_CHUNK_IO_COL_THRESHOLD
+/* Definitions for chunk opt mode property. */
+#define H5D_MPIO_ACTUAL_CHUNK_OPT_MODE_SIZE     sizeof(H5D_mpio_actual_chunk_opt_mode_t)
+#define H5D_MPIO_ACTUAL_CHUNK_OPT_MODE_DEF      H5D_MPIO_NO_CHUNK_OPTIMIZATION
+/* Definitions for chunk io mode property. */
+#define H5D_MPIO_ACTUAL_IO_MODE_SIZE    sizeof(H5D_mpio_actual_io_mode_t)
+#define H5D_MPIO_ACTUAL_IO_MODE_DEF     H5D_MPIO_NO_COLLECTIVE
 /* Definitions for EDC property */
-#define H5D_XFER_EDC_SIZE       sizeof(H5Z_EDC_t)
-#define H5D_XFER_EDC_DEF        H5Z_ENABLE_EDC
+#define H5D_XFER_EDC_SIZE           sizeof(H5Z_EDC_t)
+#define H5D_XFER_EDC_DEF            H5Z_ENABLE_EDC
 /* Definitions for filter callback function property */
-#define H5D_XFER_FILTER_CB_SIZE       sizeof(H5Z_cb_t)
-#define H5D_XFER_FILTER_CB_DEF        {NULL,NULL}
+#define H5D_XFER_FILTER_CB_SIZE     sizeof(H5Z_cb_t)
+#define H5D_XFER_FILTER_CB_DEF      {NULL,NULL}
 /* Definitions for type conversion callback function property */
 #define H5D_XFER_CONV_CB_SIZE       sizeof(H5T_conv_cb_t)
 #define H5D_XFER_CONV_CB_DEF        {NULL,NULL}
@@ -205,6 +211,8 @@ H5P_dxfr_reg_prop(H5P_genclass_t *pclass)
     H5FD_mpio_collective_opt_t def_mpio_collective_opt_mode = H5D_XFER_MPIO_COLLECTIVE_OPT_DEF;
     unsigned def_mpio_chunk_opt_num = H5D_XFER_MPIO_CHUNK_OPT_NUM_DEF;
     unsigned def_mpio_chunk_opt_ratio = H5D_XFER_MPIO_CHUNK_OPT_RATIO_DEF;
+    H5D_mpio_actual_chunk_opt_mode_t def_mpio_actual_chunk_opt_mode = H5D_MPIO_ACTUAL_CHUNK_OPT_MODE_DEF;
+    H5D_mpio_actual_io_mode_t def_mpio_actual_io_mode = H5D_MPIO_ACTUAL_IO_MODE_DEF;
 #endif /* H5_HAVE_PARALLEL */
     H5Z_EDC_t enable_edc = H5D_XFER_EDC_DEF;            /* Default value for EDC property */
     H5Z_cb_t filter_cb = H5D_XFER_FILTER_CB_DEF;        /* Default value for filter callback */
@@ -268,7 +276,7 @@ H5P_dxfr_reg_prop(H5P_genclass_t *pclass)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class")
 
 #ifdef H5_HAVE_PARALLEL
-    /* Register the I/O transfer mode property */
+    /* Register the I/O transfer mode properties */
     if(H5P_register_real(pclass, H5D_XFER_IO_XFER_MODE_NAME, H5D_XFER_IO_XFER_MODE_SIZE, &def_io_xfer_mode, NULL, NULL, NULL, NULL, NULL, NULL, NULL) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class")
     if(H5P_register_real(pclass, H5D_XFER_MPIO_COLLECTIVE_OPT_NAME, H5D_XFER_MPIO_COLLECTIVE_OPT_SIZE, &def_mpio_collective_opt_mode, NULL, NULL, NULL, NULL, NULL, NULL, NULL) < 0)
@@ -279,6 +287,14 @@ H5P_dxfr_reg_prop(H5P_genclass_t *pclass)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class")
     if(H5P_register_real(pclass, H5D_XFER_MPIO_CHUNK_OPT_RATIO_NAME, H5D_XFER_MPIO_CHUNK_OPT_RATIO_SIZE, &def_mpio_chunk_opt_ratio, NULL, NULL, NULL, NULL, NULL, NULL, NULL) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class")
+
+    /* Register the chunk optimization mode property. */
+    if(H5P_register_real(pclass, H5D_MPIO_ACTUAL_CHUNK_OPT_MODE_NAME, H5D_MPIO_ACTUAL_CHUNK_OPT_MODE_SIZE, &def_mpio_actual_chunk_opt_mode, NULL, NULL, NULL, NULL, NULL, NULL, NULL) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class")
+
+    /* Register the actual io mode property. */
+    if(H5P_register_real(pclass, H5D_MPIO_ACTUAL_IO_MODE_NAME, H5D_MPIO_ACTUAL_IO_MODE_SIZE, &def_mpio_actual_io_mode, NULL, NULL, NULL, NULL, NULL, NULL, NULL) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class")
 #endif /* H5_HAVE_PARALLEL */
 
     /* Register the EDC property */
@@ -1483,3 +1499,74 @@ done:
     FUNC_LEAVE_API(ret_value)
 } /* end H5Pget_hyper_vector_size() */
 
+
+#ifdef H5_HAVE_PARALLEL
+/*-------------------------------------------------------------------------
+ * Function:	H5Pget_mpio_actual_chunk_opt_mode
+ *
+ * Purpose:	Retrieves the chunked io optimization scheme that library chose
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Jacob Gruber
+ *              Wednesday, May 4, 2011
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pget_mpio_actual_chunk_opt_mode(hid_t plist_id, H5D_mpio_actual_chunk_opt_mode_t *actual_chunk_opt_mode)
+{
+    H5P_genplist_t     *plist;
+    herr_t ret_value = SUCCEED;   /* return value */
+    
+    FUNC_ENTER_API(H5Pget_mpio_actual_chunk_opt_mode, FAIL)
+    H5TRACE2("e","ix", plist_id, actual_chunk_opt_mode);
+
+    /* Get the plist structure */
+    if(NULL == (plist = H5P_object_verify(plist_id, H5P_DATASET_XFER)))
+        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")
+
+    /* Return values */
+    if(actual_chunk_opt_mode)
+        if(H5P_get(plist, H5D_MPIO_ACTUAL_CHUNK_OPT_MODE_NAME, actual_chunk_opt_mode) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get value")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pget_mpio_actual_chunk_opt_mode() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5Pget_mpio_actual_io_mode
+ *
+ * Purpose:	Retrieves the type of I/O actually preformed when collective I/O
+ *		is requested.
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Jacob Gruber
+ *              Wednesday, May 4, 2011
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pget_mpio_actual_io_mode(hid_t plist_id, H5D_mpio_actual_io_mode_t * actual_io_mode)
+{
+    H5P_genplist_t     *plist;
+    herr_t ret_value = SUCCEED;   /* return value */
+    
+    FUNC_ENTER_API(H5Pget_mpio_actual_io_mode, FAIL)
+    H5TRACE2("e","ix", plist_id, actual_io_mode);
+
+    /* Get the plist structure */
+    if(NULL == (plist = H5P_object_verify(plist_id, H5P_DATASET_XFER)))
+        HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")
+
+    /* Return values */
+    if(actual_io_mode)
+        if(H5P_get(plist, H5D_MPIO_ACTUAL_IO_MODE_NAME, actual_io_mode) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get value")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pget_mpio_actual_io_mode() */
+#endif /* H5_HAVE_PARALLEL */
+
diff --git a/src/H5Ppublic.h b/src/H5Ppublic.h
index 80c028a..492a468 100644
--- a/src/H5Ppublic.h
+++ b/src/H5Ppublic.h
@@ -120,6 +120,38 @@ typedef H5P_prp_cb1_t H5P_prp_close_func_t;
 /* Define property list iteration function type */
 typedef herr_t (*H5P_iterate_t)(hid_t id, const char *name, void *iter_data);
 
+/* Actual IO mode property */
+typedef enum H5D_mpio_actual_chunk_opt_mode_t {
+    /* The default value, H5D_MPIO_NO_CHUNK_OPTIMIZATION, is used for all I/O
+     * operations that do not use chunk optimizations, including non-collective
+     * I/O and contiguous collective I/O.
+     */
+    H5D_MPIO_NO_CHUNK_OPTIMIZATION = 0,
+    H5D_MPIO_LINK_CHUNK,
+    H5D_MPIO_MULTI_CHUNK,
+    H5D_MPIO_MULTI_CHUNK_NO_OPT
+}  H5D_mpio_actual_chunk_opt_mode_t;
+
+typedef enum H5D_mpio_actual_io_mode_t {
+    /* The following four values are conveniently defined as a bit field so that
+     * we can switch from the default to indpendent or collective and then to
+     * mixed without having to check the original value. 
+     * 
+     * NO_COLLECTIVE means that either collective I/O wasn't requested or that 
+     * no I/O took place.
+     *
+     * CHUNK_INDEPENDENT means that collective I/O was requested, but the
+     * chunk optimization scheme chose independent I/O for each chunk.
+     */
+    H5D_MPIO_NO_COLLECTIVE = 0x0,
+    H5D_MPIO_CHUNK_INDEPENDENT = 0x1,
+    H5D_MPIO_CHUNK_COLLECTIVE = 0x2,
+    H5D_MPIO_CHUNK_MIXED = 0x1 | 0x2,
+
+    /* The contiguous case is separate from the bit field. */
+    H5D_MPIO_CONTIGUOUS_COLLECTIVE = 0x4
+} H5D_mpio_actual_io_mode_t; 
+
 /********************/
 /* Public Variables */
 /********************/
@@ -359,6 +391,10 @@ H5_DLL herr_t H5Pset_type_conv_cb(hid_t dxpl_id, H5T_conv_except_func_t op, void
 H5_DLL herr_t H5Pget_type_conv_cb(hid_t dxpl_id, H5T_conv_except_func_t *op, void** operate_data);
 H5_DLL herr_t H5Pset_enum_conv_overflow(hid_t plist_id, hbool_t conv_overflow);
 H5_DLL herr_t H5Pget_enum_conv_overflow(hid_t plist_id, hbool_t *conv_overflow/*out*/);
+#ifdef H5_HAVE_PARALLEL
+H5_DLL herr_t H5Pget_mpio_actual_chunk_opt_mode(hid_t plist_id, H5D_mpio_actual_chunk_opt_mode_t *actual_chunk_opt_mode);
+H5_DLL herr_t H5Pget_mpio_actual_io_mode(hid_t plist_id, H5D_mpio_actual_io_mode_t *actual_io_mode);
+#endif /* H5_HAVE_PARALLEL */
 
 /* Link creation property list (LCPL) routines */
 H5_DLL herr_t H5Pset_create_intermediate_group(hid_t plist_id, unsigned crt_intmd);