[svn-r24660] - update scratch pad data integrity. Works with IOD now.

- add object creation property to enable/disable checksum per object
  * Still not used yet.

15 files changed, 182 insertions, 101 deletions

diff --git a/src/H5Pocpl.c b/src/H5Pocpl.c
index 32f6a1b..cb68496 100644
--- a/src/H5Pocpl.c
+++ b/src/H5Pocpl.c
@@ -49,6 +49,13 @@
 /****************/
 
 /* ========= Object Creation properties ============ */
+#ifdef H5_HAVE_EFF
+/* hint for IOD to enable checksums on an object */
+#define H5O_CRT_ENABLE_CHECKSUM_SIZE    sizeof(hbool_t)
+#define H5O_CRT_ENABLE_CHECKSUM_DEF     FALSE
+#define H5O_CRT_ENABLE_CHECKSUM_ENC     H5P__encode_hbool_t
+#define H5O_CRT_ENABLE_CHECKSUM_DEC     H5P__decode_hbool_t
+#endif
 /* Definitions for the max. # of attributes to store compactly */
 #define H5O_CRT_ATTR_MAX_COMPACT_SIZE   sizeof(unsigned)
 #define H5O_CRT_ATTR_MAX_COMPACT_ENC    H5P__encode_unsigned
@@ -132,7 +139,9 @@ static const unsigned H5O_def_attr_max_compact_g = H5O_CRT_ATTR_MAX_COMPACT_DEF;
 static const unsigned H5O_def_attr_min_dense_g = H5O_CRT_ATTR_MIN_DENSE_DEF;       /* Default min. dense attribute storage settings */
 static const uint8_t H5O_def_ohdr_flags_g = H5O_CRT_OHDR_FLAGS_DEF;        /* Default object header flag settings */
 static const H5O_pline_t H5O_def_pline_g = H5O_CRT_PIPELINE_DEF;           /* Default I/O pipeline setting */
-
+#ifdef H5_HAVE_EFF
+static const hbool_t H5O_def_enable_checksum_g = H5O_CRT_ENABLE_CHECKSUM_DEF;
+#endif
 
 
 /*-------------------------------------------------------------------------
@@ -154,6 +163,14 @@ H5P__ocrt_reg_prop(H5P_genclass_t *pclass)
 
     FUNC_ENTER_STATIC
 
+#ifdef H5_HAVE_EFF
+    if(H5P_register_real(pclass, H5O_CRT_ENABLE_CHECKSUM_NAME, H5O_CRT_ENABLE_CHECKSUM_SIZE, 
+                         &H5O_def_enable_checksum_g,
+                         NULL, NULL, NULL, H5O_CRT_ENABLE_CHECKSUM_ENC, H5O_CRT_ENABLE_CHECKSUM_DEC, 
+                         NULL, NULL, NULL, NULL) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class")
+#endif
+
     /* Register max. compact attribute storage property */
     if(H5P_register_real(pclass, H5O_CRT_ATTR_MAX_COMPACT_NAME, H5O_CRT_ATTR_MAX_COMPACT_SIZE, &H5O_def_attr_max_compact_g, 
             NULL, NULL, NULL, H5O_CRT_ATTR_MAX_COMPACT_ENC, H5O_CRT_ATTR_MAX_COMPACT_DEC,
diff --git a/src/H5Sselect.c b/src/H5Sselect.c
index eabfc09..58d25f6 100644
--- a/src/H5Sselect.c
+++ b/src/H5Sselect.c
@@ -2148,32 +2148,22 @@ done:
 } /* end H5S_get_offsets() */
 
 #ifdef H5_HAVE_EFF
-
-/*-------------------------------------------------------------------------
- * Function:	H5S_checksum
- *
- * Purpose:	Computes a checksum for a buffer with a dataspace 
- *              selection using the HDF5 fletcher checksume routines.
- *
- * Return:	Returns a 32-bit value.  Every bit of the key affects every bit of
- *              the return value.  Two keys differing by one or two bits will have
- *              totally different hash values.
- *
- * Programmer:	Mohamad Chaarawi
- *              June 2013
- *
- *-------------------------------------------------------------------------
- */
 uint64_t
 H5S_checksum(const void *buf, size_t elmt_size, size_t nelmts, const H5S_t *space)
 {
+    H5S_sel_iter_t iter;    /* Memory selection iteration info */
+    hbool_t iter_init = 0;  /* Memory selection iteration info has been initialized */
     hsize_t _off[H5D_IO_VECTOR_SIZE];      /* Array to store sequence offsets in memory */
     hsize_t *off = NULL;    /* Pointer to sequence offsets in memory */
     size_t _len[H5D_IO_VECTOR_SIZE];       /* Array to store sequence lengths in memory */
     size_t *len = NULL;     /* Pointer to sequence lengths in memory */
-    H5S_sel_iter_t iter;    /* Memory selection iteration info */
-    hbool_t iter_init = 0;  /* Memory selection iteration info has been initialized */
     size_t nseq;            /* Number of sequences generated */
+    size_t nelem;           /* Number of elements used in sequences */
+    size_t i;
+    const uint8_t *p = (const uint8_t *)buf;
+    const char *hash_method = "crc64";
+    size_t hash_size;
+    mchecksum_object_t checksum;
     uint64_t ret_value = 0;
 
     FUNC_ENTER_NOAPI_NOINIT
@@ -2181,57 +2171,39 @@ H5S_checksum(const void *buf, size_t elmt_size, size_t nelmts, const H5S_t *spac
     len = _len;
     off = _off;
 
-    /* Check for only one element in selection */
-    if(nelmts == 1) {
-        size_t buf_size = elmt_size * nelmts;
-
-        if(H5S_SELECT_OFFSET(space, off) < 0)
-            HGOTO_ERROR(H5E_INTERNAL, H5E_UNSUPPORTED, 0, "can't retrieve memory selection offset");
-
-        ret_value = H5_checksum_crc64(buf, buf_size);
-    } /* end if */
-    else {
-        size_t nelem;           /* Number of elements used in sequences */
-        size_t i;
-        const uint8_t *p = (const uint8_t *)buf;
-        const char *hash_method = "crc64";
-        size_t hash_size;
-        mchecksum_object_t checksum;
-
-        /* Initialize iterator */
-        if(H5S_select_iter_init(&iter, space, elmt_size) < 0)
-            HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, 0, "unable to initialize selection iterator")
-        iter_init = 1;
+    /* Initialize iterator */
+    if(H5S_select_iter_init(&iter, space, elmt_size) < 0)
+        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, 0, "unable to initialize selection iterator")
+            iter_init = 1;
 
-        nseq = 0;
+    nseq = 0;
 
-        /* Initialize checksum */
-        mchecksum_init(hash_method, &checksum);
+    /* Initialize checksum */
+    mchecksum_init(hash_method, &checksum);
 
-        /* Loop, until all bytes are processed */
-        while(nelmts > 0) {
-            /* Get sequences for selection */
-            if(H5S_SELECT_GET_SEQ_LIST(space, 0, &iter, H5D_IO_VECTOR_SIZE, nelmts, &nseq, 
-                                       &nelem, off, len) < 0)
-                HGOTO_ERROR(H5E_INTERNAL, H5E_UNSUPPORTED, 0, "sequence length generation failed");
+    /* Loop, until all bytes are processed */
+    while(nelmts > 0) {
+        /* Get sequences for selection */
+        if(H5S_SELECT_GET_SEQ_LIST(space, 0, &iter, H5D_IO_VECTOR_SIZE, nelmts, &nseq, 
+                                   &nelem, off, len) < 0)
+            HGOTO_ERROR(H5E_INTERNAL, H5E_UNSUPPORTED, 0, "sequence length generation failed");
 
-            for(i=0 ; i<nseq ; i++) {
-                mchecksum_update(checksum, p+off[i], len[i]);
-            }
-            nelmts -= nelem;
-        } /* end while */
+        for(i=0 ; i<nseq ; i++) {
+            mchecksum_update(checksum, p+off[i], len[i]);
+        }
+        nelmts -= nelem;
+    } /* end while */
 
-        /* Get size of checksum */
-        hash_size = mchecksum_get_size(checksum);
+    /* Get size of checksum */
+    hash_size = mchecksum_get_size(checksum);
 
-        assert(hash_size == sizeof(uint64_t));
+    assert(hash_size == sizeof(uint64_t));
 
-        /* get checksum value */
-        mchecksum_get(checksum, &ret_value, hash_size, 1);
+    /* get checksum value */
+    mchecksum_get(checksum, &ret_value, hash_size, 1);
 
-        /* Destroy checksum */
-        mchecksum_destroy(checksum);
-    } /* end else */
+    /* Destroy checksum */
+    mchecksum_destroy(checksum);
 
 done:
     /* Release memory selection iterator */
diff --git a/src/H5VLiod.c b/src/H5VLiod.c
index 695927e..f39f987 100644
--- a/src/H5VLiod.c
+++ b/src/H5VLiod.c
@@ -973,6 +973,81 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5Pset_ocpl_enable_checksum
+ *
+ * Purpose:     Set a boolean flag on the object creation property list 
+ *              to indicate to the VOL plugin to enable checksum on the 
+ *              object to be created.
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:  Mohamad Chaarawi
+ *              January, 2014
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pset_ocpl_enable_checksum(hid_t ocpl_id, hbool_t flag)
+{
+    H5P_genplist_t *plist = NULL;      /* Property list pointer */
+    herr_t ret_value = SUCCEED; /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE2("e", "ib", ocpl_id, flag);
+
+    if(ocpl_id == H5P_DEFAULT)
+        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list")
+
+    /* Check arguments */
+    if(NULL == (plist = H5P_object_verify(ocpl_id, H5P_OBJECT_CREATE)))
+        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a ocpl")
+
+    /* Set the transfer mode */
+    if(H5P_set(plist, H5O_CRT_ENABLE_CHECKSUM_NAME, &flag) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to set value")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pset_ocpl_enable_checksum() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5Pget_ocpl_enable_checksum
+ *
+ * Purpose:     Retrieve a boolean flag on the object creation property 
+ *              list that indicates whether checksuming on this object 
+ *              is enabled or not.
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:  Mohamad Chaarawi
+ *              January, 2014
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pget_ocpl_enable_checksum(hid_t ocpl_id, hbool_t *flag/*out*/)
+{
+    H5P_genplist_t *plist = NULL;              /* Property list pointer */
+    herr_t      ret_value = SUCCEED;    /* Return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE2("e", "ix", ocpl_id, flag);
+
+    if(NULL == (plist = H5P_object_verify(ocpl_id, H5P_OBJECT_CREATE)))
+        HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a ocpl")
+
+    /* Get the transfer mode */
+    if(flag)
+        if(H5P_get(plist, H5O_CRT_ENABLE_CHECKSUM_NAME, flag) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "unable to get value")
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pget_ocpl_enable_checksum() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5Pset_dxpl_checksum
  *
  * Purpose:     Modify the dataset transfer property list to set a
@@ -3202,7 +3277,7 @@ H5VL_iod_dataset_write(void *_dset, hid_t mem_type_id, hid_t mem_space_id,
     char fake_char;
     int *status = NULL;
     H5VL_iod_write_info_t *info; /* info struct used to manage I/O parameters once the operation completes*/
-    uint64_t internal_cs; /* internal checksum calculated in this function */
+    uint64_t internal_cs = 0; /* internal checksum calculated in this function */
     H5VL_iod_request_t **parent_reqs = NULL;
     size_t num_parents = 0;
     hid_t trans_id;
@@ -3367,6 +3442,7 @@ H5VL_iod_dataset_write(void *_dset, hid_t mem_type_id, hid_t mem_space_id,
     input.trans_num = tr->trans_num;
     input.rcxt_num  = tr->c_version;
     input.cs_scope = dset->common.file->md_integrity_scope;
+    input.axe_id = g_axe_id;
 
     status = (int *)malloc(sizeof(int));
 
@@ -3374,7 +3450,7 @@ H5VL_iod_dataset_write(void *_dset, hid_t mem_type_id, hid_t mem_space_id,
     printf("Dataset Write, axe id %"PRIu64"\n", g_axe_id);
 #endif
 
-    /* setup info struct for I/O request 
+    /* setup info struct for I/O request
        This is to manage the I/O operation once the wait is called. */
     if(NULL == (info = (H5VL_iod_write_info_t *)H5MM_calloc(sizeof(H5VL_iod_write_info_t))))
 	HGOTO_ERROR(H5E_DATASET, H5E_NOSPACE, FAIL, "can't allocate a request");
diff --git a/src/H5VLiod.h b/src/H5VLiod.h
index 07b74b8..719967e 100644
--- a/src/H5VLiod.h
+++ b/src/H5VLiod.h
@@ -48,7 +48,7 @@ extern "C" {
 #define H5D_XFER_CHECKSUM_NAME "checksum"
 #define H5D_XFER_CHECKSUM_PTR_NAME "checksum_ptr"
 #define H5D_CRT_APPEND_ONLY_NAME "append_only"
-
+#define H5O_CRT_ENABLE_CHECKSUM_NAME "enable_obj_checksum"
 
 H5_DLL H5VL_class_t *H5VL_iod_init(void);
 H5_DLL herr_t H5Pset_fapl_iod(hid_t fapl_id, MPI_Comm comm, MPI_Info info);
@@ -56,6 +56,8 @@ H5_DLL herr_t EFF_start_server(MPI_Comm comm, MPI_Info info);
 H5_DLL herr_t EFF_init(MPI_Comm comm, MPI_Info info);
 H5_DLL herr_t EFF_finalize(void);
 
+H5_DLL herr_t H5Pset_ocpl_enable_checksum(hid_t ocpl_id, hbool_t flag);
+H5_DLL herr_t H5Pget_ocpl_enable_checksum(hid_t ocpl_id, hbool_t *flag);
 H5_DLL herr_t H5Pset_dxpl_checksum(hid_t dxpl_id, uint64_t value);
 H5_DLL herr_t H5Pget_dxpl_checksum(hid_t dxpl_id, uint64_t *value);
 H5_DLL herr_t H5Pset_dxpl_checksum_ptr(hid_t dxpl_id, uint64_t *value);
diff --git a/src/H5VLiod_attr.c b/src/H5VLiod_attr.c
index 602060d..d14b7c0 100644
--- a/src/H5VLiod_attr.c
+++ b/src/H5VLiod_attr.c
@@ -172,7 +172,7 @@ H5VL_iod_server_attr_create_cb(AXE_engine_t UNUSED axe_engine,
 
         if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
             /* verify scratch pad integrity */
-            if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+            if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
                 HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
         }
 
@@ -313,7 +313,7 @@ H5VL_iod_server_attr_open_cb(AXE_engine_t UNUSED axe_engine,
 
         if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
             /* verify scratch pad integrity */
-            if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+            if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
                 HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
         }
 
@@ -359,7 +359,7 @@ H5VL_iod_server_attr_open_cb(AXE_engine_t UNUSED axe_engine,
 
     if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
         /* verify scratch pad integrity */
-        if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+        if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
             HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
     }
 
@@ -833,7 +833,7 @@ H5VL_iod_server_attr_exists_cb(AXE_engine_t UNUSED axe_engine,
 
         if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
             /* verify scratch pad integrity */
-            if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+            if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
                 HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
         }
 
@@ -944,7 +944,7 @@ H5VL_iod_server_attr_rename_cb(AXE_engine_t UNUSED axe_engine,
 
         if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
             /* verify scratch pad integrity */
-            if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+            if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
                 HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
         }
 
@@ -1076,7 +1076,7 @@ H5VL_iod_server_attr_remove_cb(AXE_engine_t UNUSED axe_engine,
 
         if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
             /* verify scratch pad integrity */
-            if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+            if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
                 HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
         }
 
@@ -1126,7 +1126,7 @@ H5VL_iod_server_attr_remove_cb(AXE_engine_t UNUSED axe_engine,
 
     if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
         /* verify scratch pad integrity */
-        if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+        if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
             HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
     }
 
diff --git a/src/H5VLiod_common.c b/src/H5VLiod_common.c
index afb6089..38e60fc 100644
--- a/src/H5VLiod_common.c
+++ b/src/H5VLiod_common.c
@@ -930,8 +930,8 @@ H5_checksum_crc64(const void *buf, size_t buf_size)
 {
     const char *hash_method = "crc64";
     size_t hash_size;
-    uint64_t hash;
     mchecksum_object_t checksum;
+    uint64_t ret_value = 0;
 
     /* Initialize checksum */
     mchecksum_init(hash_method, &checksum);
@@ -945,12 +945,12 @@ H5_checksum_crc64(const void *buf, size_t buf_size)
     assert(hash_size == sizeof(uint64_t));
 
     /* get checksum value */
-    mchecksum_get(checksum, &hash, hash_size, 1);
+    mchecksum_get(checksum, &ret_value, hash_size, 1);
 
     /* Destroy checksum */
     mchecksum_destroy(checksum);
 
-    return hash;
+    return ret_value;
 }
 
 uint64_t 
@@ -958,9 +958,9 @@ H5_checksum_crc64_segments(hg_bulk_segment_t *segments, size_t count)
 {
     const char *hash_method = "crc64";
     size_t hash_size;
-    uint64_t hash;
     size_t i;
     mchecksum_object_t checksum;
+    uint64_t ret_value;
 
     /* Initialize checksum */
     mchecksum_init(hash_method, &checksum);
@@ -976,12 +976,12 @@ H5_checksum_crc64_segments(hg_bulk_segment_t *segments, size_t count)
     assert(hash_size == sizeof(uint64_t));
 
     /* get checksum value */
-    mchecksum_get(checksum, &hash, hash_size, 1);
+    mchecksum_get(checksum, &ret_value, hash_size, 1);
 
     /* Destroy checksum */
     mchecksum_destroy(checksum);
 
-    return hash;
+    return ret_value;
 }
 
 uint64_t 
@@ -989,9 +989,9 @@ H5_checksum_crc64_fragments(void **buf, size_t *buf_size, size_t count)
 {
     const char *hash_method = "crc64";
     size_t hash_size;
-    uint64_t hash;
     size_t i;
     mchecksum_object_t checksum;
+    uint64_t ret_value;
 
     /* Initialize checksum */
     mchecksum_init(hash_method, &checksum);
@@ -1007,10 +1007,10 @@ H5_checksum_crc64_fragments(void **buf, size_t *buf_size, size_t count)
     assert(hash_size == sizeof(uint64_t));
 
     /* get checksum value */
-    mchecksum_get(checksum, &hash, hash_size, 1);
+    mchecksum_get(checksum, &ret_value, hash_size, 1);
 
     /* Destroy checksum */
     mchecksum_destroy(checksum);
 
-    return hash;
+    return ret_value;
 }
diff --git a/src/H5VLiod_dset.c b/src/H5VLiod_dset.c
index 43c9eea..1e617f3 100644
--- a/src/H5VLiod_dset.c
+++ b/src/H5VLiod_dset.c
@@ -231,9 +231,10 @@ H5VL_iod_server_dset_create_cb(AXE_engine_t UNUSED axe_engine,
 
     /* set scratch pad in dataset */
     if(cs_scope & H5_CHECKSUM_IOD) {
-        iod_checksum_t sp_cs;
+        iod_checksum_t sp_cs = 0;
 
         sp_cs = H5_checksum_crc64(&sp, sizeof(sp));
+
         if (iod_obj_set_scratch(dset_oh.wr_oh, wtid, &sp, &sp_cs, NULL) < 0)
             HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "can't set scratch pad");
     }
@@ -398,7 +399,7 @@ H5VL_iod_server_dset_open_cb(AXE_engine_t UNUSED axe_engine,
 
     if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
         /* verify scratch pad integrity */
-        if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+        if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
             HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
     }
 
diff --git a/src/H5VLiod_dtype.c b/src/H5VLiod_dtype.c
index 4b2a9dc..010ba5e 100644
--- a/src/H5VLiod_dtype.c
+++ b/src/H5VLiod_dtype.c
@@ -326,7 +326,7 @@ H5VL_iod_server_dtype_open_cb(AXE_engine_t UNUSED axe_engine,
 
     if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
         /* verify scratch pad integrity */
-        if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+        if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
             HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
     }
 
diff --git a/src/H5VLiod_file.c b/src/H5VLiod_file.c
index 53e90f5..7d78437 100644
--- a/src/H5VLiod_file.c
+++ b/src/H5VLiod_file.c
@@ -59,6 +59,7 @@ H5VL_iod_server_file_create_cb(AXE_engine_t UNUSED axe_engine,
     iod_ret_t ret, root_ret;
     iod_trans_id_t first_tid = 0;
     uint32_t cs_scope = 0;
+    iod_hint_list_t *con_open_hint = NULL;
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI_NOINIT
@@ -78,8 +79,14 @@ H5VL_iod_server_file_create_cb(AXE_engine_t UNUSED axe_engine,
     if(H5Pget_metadata_integrity_scope(input->fapl_id, &cs_scope) < 0)
         HGOTO_ERROR2(H5E_PLIST, H5E_CANTGET, FAIL, "can't get scope for data integrity checks");
 
+    if(cs_scope & H5_CHECKSUM_IOD) {
+        con_open_hint = (iod_hint_list_t *)malloc(sizeof(iod_hint_list_t) + sizeof(iod_hint_t));
+        con_open_hint->num_hint = 1;
+        con_open_hint->hint[0].key = "iod_con_scratch_cksum";
+    }
+
     /* Create the Container */
-    ret = iod_container_open(input->name, NULL, mode, &coh, NULL);
+    ret = iod_container_open(input->name, con_open_hint, mode, &coh, NULL);
     if(ret < 0)
         HGOTO_ERROR_IOD(ret, FAIL, "can't create container");
 
@@ -137,6 +144,7 @@ H5VL_iod_server_file_create_cb(AXE_engine_t UNUSED axe_engine,
             iod_checksum_t sp_cs;
 
             sp_cs = H5_checksum_crc64(&sp, sizeof(sp));
+
             /* set scratch pad in root group */
             ret = iod_obj_set_scratch(root_oh.wr_oh, first_tid, &sp, &sp_cs, NULL);
             if(ret < 0)
@@ -214,6 +222,11 @@ done:
     input = (file_create_in_t *)H5MM_xfree(input);
     op_data = (op_data_t *)H5MM_xfree(op_data);
 
+    if(con_open_hint) {
+        free(con_open_hint);
+        con_open_hint = NULL;
+    }
+
     FUNC_LEAVE_NOAPI_VOID
 } /* end H5VL_iod_server_file_create_cb() */
 
@@ -302,7 +315,7 @@ H5VL_iod_server_file_open_cb(AXE_engine_t UNUSED axe_engine,
 
     if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
         /* verify scratch pad integrity */
-        if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+        if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
             HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
     }
 
@@ -519,7 +532,7 @@ H5VL_iod_server_file_close_cb(AXE_engine_t UNUSED axe_engine,
 
         if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
             /* verify scratch pad integrity */
-            if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+            if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
                 HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
         }
 
diff --git a/src/H5VLiod_group.c b/src/H5VLiod_group.c
index 5047009..94805d7 100644
--- a/src/H5VLiod_group.c
+++ b/src/H5VLiod_group.c
@@ -284,7 +284,7 @@ H5VL_iod_server_group_open_cb(AXE_engine_t UNUSED axe_engine,
 
     if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
         /* verify scratch pad integrity */
-        if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+        if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
             HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
     }
 
diff --git a/src/H5VLiod_link.c b/src/H5VLiod_link.c
index 35ea1c7..89d08d1 100644
--- a/src/H5VLiod_link.c
+++ b/src/H5VLiod_link.c
@@ -106,7 +106,7 @@ H5VL_iod_server_link_create_cb(AXE_engine_t UNUSED axe_engine,
 
             if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
                 /* verify scratch pad integrity */
-                if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+                if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
                     HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
             }
 
@@ -303,7 +303,7 @@ H5VL_iod_server_link_move_cb(AXE_engine_t UNUSED axe_engine,
             HGOTO_ERROR2(H5E_FILE, H5E_CANTINIT, FAIL, "can't get scratch pad for object");
         if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
             /* verify scratch pad integrity */
-            if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+            if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
                 HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
         }
 
@@ -775,7 +775,7 @@ H5VL_iod_server_link_remove_cb(AXE_engine_t UNUSED axe_engine,
 
         if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
             /* verify scratch pad integrity */
-            if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+            if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
                 HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
         }
 
diff --git a/src/H5VLiod_map.c b/src/H5VLiod_map.c
index 277e2ff..63221bd 100644
--- a/src/H5VLiod_map.c
+++ b/src/H5VLiod_map.c
@@ -284,7 +284,7 @@ H5VL_iod_server_map_open_cb(AXE_engine_t UNUSED axe_engine,
 
     if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
         /* verify scratch pad integrity */
-        if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+        if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
             HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
     }
 
diff --git a/src/H5VLiod_obj.c b/src/H5VLiod_obj.c
index aa60d04..d5d171d 100644
--- a/src/H5VLiod_obj.c
+++ b/src/H5VLiod_obj.c
@@ -138,7 +138,7 @@ H5VL_iod_server_object_open_cb(AXE_engine_t UNUSED axe_engine,
 
         if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
             /* verify scratch pad integrity */
-            if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+            if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
                 HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
         }
 
@@ -352,7 +352,7 @@ H5VL_iod_server_object_copy_cb(AXE_engine_t UNUSED axe_engine,
 
     if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
         /* verify scratch pad integrity */
-        if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+        if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
             HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
     }
 
@@ -604,7 +604,7 @@ H5VL_iod_server_object_get_info_cb(AXE_engine_t UNUSED axe_engine,
 
         if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
             /* verify scratch pad integrity */
-            if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+            if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
                 HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
         }
 
@@ -747,7 +747,7 @@ H5VL_iod_server_object_set_comment_cb(AXE_engine_t UNUSED axe_engine,
 
         if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
             /* verify scratch pad integrity */
-            if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+            if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
                 HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
         }
 
@@ -855,7 +855,7 @@ H5VL_iod_server_object_get_comment_cb(AXE_engine_t UNUSED axe_engine,
 
         if(sp_cs && (cs_scope & H5_CHECKSUM_IOD)) {
             /* verify scratch pad integrity */
-            if(H5VL_iod_verify_scratch_pad(sp, sp_cs) < 0)
+            if(H5VL_iod_verify_scratch_pad(&sp, sp_cs) < 0)
                 HGOTO_ERROR2(H5E_SYM, H5E_CANTINIT, FAIL, "Scratch Pad failed integrity check");
         }
 
diff --git a/src/H5VLiod_server.h b/src/H5VLiod_server.h
index d18367e..1b004de 100644
--- a/src/H5VLiod_server.h
+++ b/src/H5VLiod_server.h
@@ -415,7 +415,7 @@ H5_DLL herr_t H5VL_iod_get_metadata(iod_handle_t oh, iod_trans_id_t tid, H5VL_io
 H5_DLL herr_t H5VL__iod_server_adjust_buffer(hid_t from_type_id, hid_t to_type_id, size_t nelmts, 
                                              hid_t dxpl_id, size_t size, void **buf, 
                                              hbool_t *is_vl_data, size_t *_buf_size);
-H5_DLL herr_t H5VL_iod_verify_scratch_pad(scratch_pad sp, iod_checksum_t iod_cs);
+H5_DLL herr_t H5VL_iod_verify_scratch_pad(scratch_pad *sp, iod_checksum_t iod_cs);
 H5_DLL herr_t H5VL__iod_server_final_io(iod_handle_t iod_oh, hid_t space_id, size_t elmt_size,
                                         hbool_t write_op, void *buf, size_t buf_size, 
                                         iod_checksum_t cs, uint32_t cs_scope, iod_trans_id_t tid);
diff --git a/src/H5VLiod_util.c b/src/H5VLiod_util.c
index 38780b0..df86b7f 100644
--- a/src/H5VLiod_util.c
+++ b/src/H5VLiod_util.c
@@ -1060,17 +1060,17 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t 
-H5VL_iod_verify_scratch_pad(scratch_pad sp, iod_checksum_t iod_cs)
+H5VL_iod_verify_scratch_pad(scratch_pad *sp, iod_checksum_t iod_cs)
 {
     iod_checksum_t computed_cs = 0;
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI_NOINIT_NOERR
 
-    computed_cs = H5_checksum_crc64(&sp, sizeof(sp));
+    computed_cs = H5_checksum_crc64(sp, sizeof(scratch_pad));
 
     if(computed_cs != iod_cs) {
-        fprintf(stderr, "Scratch pad integrity check failed. IOD cs = %"PRIu64", Computed cs = %"PRIu64"",
+        fprintf(stderr, "Scratch pad integrity check failed. IOD cs = %"PRIu64", Computed cs = %"PRIu64"\n",
                 iod_cs, computed_cs);
         ret_value = FAIL;
     }