Sync with develop (#3737)

* Correct ld in format strings in cmpd_dset.c (#3697)

Removes clang warnings

* Clean up comments. (#3695)

* Add NVidia compiler support and CI (#3686)

* Work around Theta system issue failure in links test (#3710)

When the Subfiling VFD is enabled, the links test may
try to initialize the Subfiling VFD and call MPI_Init_thread.
On Theta, this appears to have an issue that will cause
the links test to fail. Reworked the test to check for
the same conditions in a more roundabout way that doesn't
involved initializing the Subfiling VFD

* Fix issue with unmatched messages in ph5diff (#3719)

* provide an alternative to mapfile for older bash (#3717)

* Attempt to quiet some warnings with cray compilers. (#3724)

* Fix CMake VOL passthrough tests by copying files to correct directory (#3721)

* Develop intel split (#3722)

* Split intel compiler flags into sub-folders
* Update Intel options for warnings
* Mostly CMake, Autotools needs additional work

* Fixes and adjustments to t_filters_parallel (#3714)

Broadcast number of datasets to create in multi-dataset I/O cases
so that interference with random number generation doesn't cause
mismatches between ranks

Set fill time for datasets to "never" by default and adjust on a
per-test basis to avoid writing fill values to chunks when it's
unnecessary

Reduce number of loops run in some tests when performing multi-dataset
I/O

Fix an issue in the "fill time never" test where data verification
could fill if file space reuse causes application buffers to be
filled with chosen fill value when reading from datasets with
uninitialized storage

Skip multi-chunk I/O test configurations for multi-dataset I/O
configurations when the TestExpress level is > 1 since those
tests can be more stressful on the file system

Disable use of persistent file free space management for now
since it occasionally runs into an infinite loop in the library's
free space management code

* Suppress cast-qual warning in H5TB Fortran wrapper (#3728)

This interface is fundamentally broken, const-wise.

* Add new API function H5Pget_actual_select_io_mode() (#2974)

This function allows the user to determine if the library performed selection I/O, vector I/O, or scalar (legacy) I/O during the last HDF5 operation performed with the provided DXPL. Expanded existing tests to check this functionality.

* Test scripts now execute in-source with creation of tmp dir (#3723)

Fixes a few issues created in #3580:

* Fixes a problem where committed tools test files were deleted when cleaning after an in-source build
* Fixes issues with test file paths in Autotools tools test scripts

* Add -h and --help as flags in h5cc & h5fc (#3729)

Adds these common help flags in addition to -help

* Update the library version matrix for H5Pset_libver_bounds() (#3702)

* Fixed #3524

Added 1.12, 1.14, and 1.16 to the table for libver bounds in the H5Pset_libver_bounds docs.

* Remove references to LIBVER_V116

---------

Co-authored-by: H. Joe Lee <hyoklee@hdfgroup.org>
Co-authored-by: Allen Byrne <50328838+byrnHDF@users.noreply.github.com>
Co-authored-by: Scot Breitenfeld <brtnfld@hdfgroup.org>
Co-authored-by: Dana Robinson <43805+derobins@users.noreply.github.com>
Co-authored-by: Neil Fortner <fortnern@gmail.com>
Co-authored-by: Glenn Song <43005495+glennsong09@users.noreply.github.com>
Co-authored-by: bmribler <39579120+bmribler@users.noreply.github.com>

8 files changed, 568 insertions, 114 deletions

diff --git a/src/H5CX.c b/src/H5CX.c
index b3b2fca..c46c58a 100644
--- a/src/H5CX.c
+++ b/src/H5CX.c
@@ -299,6 +299,11 @@ typedef struct H5CX_t {
     bool no_selection_io_cause_set; /* Whether reason for not performing selection I/O is set */
     bool no_selection_io_cause_valid; /* Whether reason for not performing selection I/O is valid */
 
+    uint32_t
+            actual_selection_io_mode; /* Actual selection I/O mode used (H5D_ACTUAL_SELECTION_IO_MODE_NAME) */
+    hbool_t actual_selection_io_mode_set;   /* Whether actual selection I/O mode is set */
+    hbool_t actual_selection_io_mode_valid; /* Whether actual selection I/O mode is valid */
+
     /* Cached LCPL properties */
     H5T_cset_t encoding;                 /* Link name character encoding */
     bool       encoding_valid;           /* Whether link name character encoding is valid */
@@ -380,6 +385,8 @@ typedef struct H5CX_dxpl_cache_t {
     H5D_selection_io_mode_t selection_io_mode;     /* Selection I/O mode (H5D_XFER_SELECTION_IO_MODE_NAME) */
     uint32_t                no_selection_io_cause; /* Reasons for not performing selection I/O
                                                             (H5D_XFER_NO_SELECTION_IO_CAUSE_NAME) */
+    uint32_t actual_selection_io_mode;             /* Actual selection I/O mode
+                                                         (H5D_XFER_ACTUAL_SELECTION_IO_MODE_NAME) */
     bool modify_write_buf;                         /* Whether the library can modify write buffers */
 } H5CX_dxpl_cache_t;
 
@@ -571,13 +578,18 @@ H5CX_init(void)
 
     /* Get the selection I/O mode */
     if (H5P_get(dx_plist, H5D_XFER_SELECTION_IO_MODE_NAME, &H5CX_def_dxpl_cache.selection_io_mode) < 0)
-        HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "Can't retrieve parallel transfer method");
+        HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "Can't retrieve selection I/O mode");
 
     /* Get the local & global reasons for breaking selection I/O values */
     if (H5P_get(dx_plist, H5D_XFER_NO_SELECTION_IO_CAUSE_NAME, &H5CX_def_dxpl_cache.no_selection_io_cause) <
         0)
         HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "Can't retrieve cause for no selection I/O");
 
+    /* Get the actual selection I/O mode */
+    if (H5P_get(dx_plist, H5D_XFER_ACTUAL_SELECTION_IO_MODE_NAME,
+                &H5CX_def_dxpl_cache.actual_selection_io_mode) < 0)
+        HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "Can't retrieve actual selection I/O mode");
+
     /* Get the modify write buffer property */
     if (H5P_get(dx_plist, H5D_XFER_MODIFY_WRITE_BUF_NAME, &H5CX_def_dxpl_cache.modify_write_buf) < 0)
         HGOTO_ERROR(H5E_CONTEXT, H5E_CANTGET, FAIL, "Can't retrieve modify write buffer property");
@@ -2515,6 +2527,47 @@ done:
 } /* end H5CX_get_no_selection_io_cause() */
 
 /*-------------------------------------------------------------------------
+ * Function:    H5CX_get_actual_selection_io_mode
+ *
+ * Purpose:     Retrieves the actual I/O mode (scalar, vector, and/or selection) for the current API call
+ *context.
+ *
+ * Return:      Non-negative on success / Negative on failure
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5CX_get_actual_selection_io_mode(uint32_t *actual_selection_io_mode)
+{
+    H5CX_node_t **head      = NULL;    /* Pointer to head of API context list */
+    herr_t        ret_value = SUCCEED; /* Return value */
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Sanity check */
+    assert(actual_selection_io_mode);
+    head = H5CX_get_my_context(); /* Get the pointer to the head of the API context, for this thread */
+    assert(head && *head);
+    assert(H5P_DEFAULT != (*head)->ctx.dxpl_id);
+
+    /* This property is a special case - we want to wipe out any previous setting.  Copy the default setting
+     * if it has not been set yet. */
+    if ((*head)->ctx.dxpl_id != H5P_DATASET_XFER_DEFAULT && !(*head)->ctx.actual_selection_io_mode_set &&
+        !(*head)->ctx.actual_selection_io_mode_valid) {
+        (*head)->ctx.actual_selection_io_mode     = H5CX_def_dxpl_cache.actual_selection_io_mode;
+        (*head)->ctx.actual_selection_io_mode_set = true;
+    }
+    H5CX_RETRIEVE_PROP_VALID_SET(dxpl, H5P_DATASET_XFER_DEFAULT, H5D_XFER_ACTUAL_SELECTION_IO_MODE_NAME,
+                                 actual_selection_io_mode)
+
+    /* Get the value */
+    *actual_selection_io_mode = (*head)->ctx.actual_selection_io_mode;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5CX_get_actual_selection_io_mode() */
+
+/*-------------------------------------------------------------------------
  * Function:    H5CX_get_modify_write_buf
  *
  * Purpose:     Retrieves the modify write buffer property for the current API call context.
@@ -3443,7 +3496,7 @@ done:
 #endif /* H5_HAVE_PARALLEL */
 
 /*-------------------------------------------------------------------------
- * Function:    H5CX_set_no_selecction_io_cause
+ * Function:    H5CX_set_no_selection_io_cause
  *
  * Purpose:     Sets the reason for not performing selection I/O for
  *              the current API call context.
@@ -3472,7 +3525,39 @@ H5CX_set_no_selection_io_cause(uint32_t no_selection_io_cause)
     } /* end if */
 
     FUNC_LEAVE_NOAPI_VOID
-} /* end H5CX_set_no_selectiion_io_cause() */
+} /* end H5CX_set_no_selection_io_cause() */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5CX_set_actual_selection_io_mode
+ *
+ * Purpose:     Sets the actual selection I/O mode for the current API
+ *              call context.
+ *
+ * Return:      <none>
+ *
+ *-------------------------------------------------------------------------
+ */
+void
+H5CX_set_actual_selection_io_mode(uint32_t actual_selection_io_mode)
+{
+    H5CX_node_t **head = NULL; /* Pointer to head of API context list */
+
+    FUNC_ENTER_NOAPI_NOINIT_NOERR
+
+    /* Sanity checks */
+    head = H5CX_get_my_context(); /* Get the pointer to the head of the API context, for this thread */
+    assert(head && *head);
+    assert((*head)->ctx.dxpl_id != H5P_DEFAULT);
+
+    /* If we're using the default DXPL, don't modify it */
+    if ((*head)->ctx.dxpl_id != H5P_DATASET_XFER_DEFAULT) {
+        /* Cache the value for later, marking it to set in DXPL when context popped */
+        (*head)->ctx.actual_selection_io_mode     = actual_selection_io_mode;
+        (*head)->ctx.actual_selection_io_mode_set = true;
+    }
+
+    FUNC_LEAVE_NOAPI_VOID
+} /* end H5CX_set_actual_selection_io_mode() */
 
 /*-------------------------------------------------------------------------
  * Function:    H5CX_get_ohdr_flags
@@ -3529,7 +3614,17 @@ H5CX__pop_common(bool update_dxpl_props)
 
     /* Check for cached DXPL properties to return to application */
     if (update_dxpl_props) {
+        /* actual_selection_io_mode is a special case - we always want to set it in the property list even if
+         * it was never set by the library, in that case it indicates no I/O was performed and we don't want
+         * to leave the (possibly incorrect) old value in the property list, so set from the default property
+         * list */
+        if ((*head)->ctx.dxpl_id != H5P_DATASET_XFER_DEFAULT && !(*head)->ctx.actual_selection_io_mode_set) {
+            (*head)->ctx.actual_selection_io_mode     = H5CX_def_dxpl_cache.actual_selection_io_mode;
+            (*head)->ctx.actual_selection_io_mode_set = true;
+        }
+
         H5CX_SET_PROP(H5D_XFER_NO_SELECTION_IO_CAUSE_NAME, no_selection_io_cause)
+        H5CX_SET_PROP(H5D_XFER_ACTUAL_SELECTION_IO_MODE_NAME, actual_selection_io_mode)
 #ifdef H5_HAVE_PARALLEL
         H5CX_SET_PROP(H5D_MPIO_ACTUAL_CHUNK_OPT_MODE_NAME, mpio_actual_chunk_opt)
         H5CX_SET_PROP(H5D_MPIO_ACTUAL_IO_MODE_NAME, mpio_actual_io_mode)
diff --git a/src/H5CXprivate.h b/src/H5CXprivate.h
index aa6883b..76812ee 100644
--- a/src/H5CXprivate.h
+++ b/src/H5CXprivate.h
@@ -116,6 +116,7 @@ H5_DLL herr_t H5CX_get_vlen_alloc_info(H5T_vlen_alloc_info_t *vl_alloc_info);
 H5_DLL herr_t H5CX_get_dt_conv_cb(H5T_conv_cb_t *cb_struct);
 H5_DLL herr_t H5CX_get_selection_io_mode(H5D_selection_io_mode_t *selection_io_mode);
 H5_DLL herr_t H5CX_get_no_selection_io_cause(uint32_t *no_selection_io_cause);
+H5_DLL herr_t H5CX_get_actual_selection_io_mode(uint32_t *actual_selection_io_mode);
 H5_DLL herr_t H5CX_get_modify_write_buf(bool *modify_write_buf);
 
 /* "Getter" routines for LCPL properties cached in API context */
@@ -162,6 +163,7 @@ H5_DLL herr_t H5CX_init(void);
 /* "Setter" routines for cached DXPL properties that must be returned to application */
 
 H5_DLL void H5CX_set_no_selection_io_cause(uint32_t no_selection_io_cause);
+H5_DLL void H5CX_set_actual_selection_io_mode(uint32_t actual_selection_io_mode);
 
 #ifdef H5_HAVE_PARALLEL
 H5_DLL void H5CX_set_mpio_actual_chunk_opt(H5D_mpio_actual_chunk_opt_mode_t chunk_opt);
diff --git a/src/H5Dio.c b/src/H5Dio.c
index 2134ce1..611518d 100644
--- a/src/H5Dio.c
+++ b/src/H5Dio.c
@@ -143,17 +143,17 @@ H5D__read(size_t count, H5D_dset_io_info_t *dset_info)
     }  /* end if */
 #endif /*H5_HAVE_PARALLEL*/
 
-    /* iterate over all dsets and construct I/O information necessary to do I/O */
+    /* Iterate over all dsets and construct I/O information necessary to do I/O */
     for (i = 0; i < count; i++) {
         haddr_t prev_tag = HADDR_UNDEF;
 
-        /* check args */
+        /* Check args */
         if (NULL == dset_info[i].dset)
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset");
         if (NULL == dset_info[i].dset->oloc.file)
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file");
 
-        /* set metadata tagging with dset oheader addr */
+        /* Set metadata tagging with dset oheader addr */
         H5AC_tag(dset_info[i].dset->oloc.addr, &prev_tag);
 
         /* Set up datatype info for operation */
@@ -173,10 +173,7 @@ H5D__read(size_t count, H5D_dset_io_info_t *dset_info)
             if (dset_info[i].nelmts > 0)
                 HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no output buffer");
 
-            /* If the buffer is nil, and 0 element is selected, make a fake buffer.
-             * This is for some MPI package like ChaMPIon on NCSA's tungsten which
-             * doesn't support this feature.
-             */
+            /* If the buffer is nil, and 0 element is selected, make a fake buffer. */
             dset_info[i].buf.vp = &fake_char;
         } /* end if */
 
@@ -191,8 +188,8 @@ H5D__read(size_t count, H5D_dset_io_info_t *dset_info)
          * rapidly changing coordinates match up), but the I/O code still has
          * difficulties with the notion.
          *
-         * To solve this, we check to see if H5S_select_shape_same() returns true,
-         * and if the ranks of the mem and file spaces are different.  If they are,
+         * To solve this, check if H5S_select_shape_same() returns true
+         * and the ranks of the mem and file spaces are different.  If so,
          * construct a new mem space that is equivalent to the old mem space, and
          * use that instead.
          *
@@ -347,7 +344,7 @@ H5D__read(size_t count, H5D_dset_io_info_t *dset_info)
             if (dset_info[i].layout_ops.mdio_init) {
                 haddr_t prev_tag = HADDR_UNDEF;
 
-                /* set metadata tagging with dset oheader addr */
+                /* Set metadata tagging with dset oheader addr */
                 H5AC_tag(dset_info[i].dset->oloc.addr, &prev_tag);
 
                 /* Make second phase IO init call */
@@ -396,7 +393,7 @@ H5D__read(size_t count, H5D_dset_io_info_t *dset_info)
             if (dset_info[i].skip_io)
                 continue;
 
-            /* set metadata tagging with dset oheader addr */
+            /* Set metadata tagging with dset object header addr */
             H5AC_tag(dset_info[i].dset->oloc.addr, &prev_tag);
 
             /* Invoke correct "high level" I/O routine */
@@ -553,18 +550,18 @@ H5D__write(size_t count, H5D_dset_io_info_t *dset_info)
         if (NULL == (store = (H5D_storage_t *)H5MM_malloc(count * sizeof(H5D_storage_t))))
             HGOTO_ERROR(H5E_DATASET, H5E_CANTALLOC, FAIL, "couldn't allocate dset storage info array buffer");
 
-    /* iterate over all dsets and construct I/O information */
+    /* Iterate over all dsets and construct I/O information */
     for (i = 0; i < count; i++) {
         bool    should_alloc_space = false; /* Whether or not to initialize dataset's storage */
         haddr_t prev_tag           = HADDR_UNDEF;
 
-        /* check args */
+        /* Check args */
         if (NULL == dset_info[i].dset)
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset");
         if (NULL == dset_info[i].dset->oloc.file)
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file");
 
-        /* set metadata tagging with dset oheader addr */
+        /* Set metadata tagging with dset oheader addr */
         H5AC_tag(dset_info[i].dset->oloc.addr, &prev_tag);
 
         /* All filters in the DCPL must have encoding enabled. */
@@ -620,10 +617,7 @@ H5D__write(size_t count, H5D_dset_io_info_t *dset_info)
             if (dset_info[i].nelmts > 0)
                 HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no input buffer");
 
-            /* If the buffer is nil, and 0 element is selected, make a fake buffer.
-             * This is for some MPI package like ChaMPIon on NCSA's tungsten which
-             * doesn't support this feature.
-             */
+            /* If the buffer is nil, and 0 element is selected, make a fake buffer. */
             dset_info[i].buf.cvp = &fake_char;
         } /* end if */
 
@@ -633,18 +627,18 @@ H5D__write(size_t count, H5D_dset_io_info_t *dset_info)
         if (!(H5S_has_extent(dset_info[i].mem_space)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "memory dataspace does not have extent set");
 
-        /* H5S_select_shape_same() has been modified to accept topologically
-         * identical selections with different rank as having the same shape
-         * (if the most rapidly changing coordinates match up), but the I/O
-         * code still has difficulties with the notion.
+        /* H5S_select_shape_same() has been modified to accept topologically identical
+         * selections with different rank as having the same shape (if the most
+         * rapidly changing coordinates match up), but the I/O code still has
+         * difficulties with the notion.
          *
-         * To solve this, we check to see if H5S_select_shape_same() returns
-         * true, and if the ranks of the mem and file spaces are different.
-         * If they are, construct a new mem space that is equivalent to the
-         * old mem space, and use that instead.
+         * To solve this, check if H5S_select_shape_same() returns true
+         * and the ranks of the mem and file spaces are different.  If so,
+         * construct a new mem space that is equivalent to the old mem space, and
+         * use that instead.
          *
-         * Note that in general, this requires us to touch up the memory buffer
-         * as well.
+         * Note that in general, this requires us to touch up the memory buffer as
+         * well.
          */
         if (dset_info[i].nelmts > 0 &&
             true == H5S_SELECT_SHAPE_SAME(dset_info[i].mem_space, dset_info[i].file_space) &&
@@ -818,11 +812,11 @@ H5D__write(size_t count, H5D_dset_io_info_t *dset_info)
                                 "unable to allocate array of selected pieces");
         }
 
-        /* loop with serial & single-dset write IO path */
+        /* Loop with serial & single-dset write IO path */
         for (i = 0; i < count; i++) {
             assert(!dset_info[i].skip_io);
 
-            /* set metadata tagging with dset oheader addr */
+            /* Set metadata tagging with dset oheader addr */
             H5AC_tag(dset_info->dset->oloc.addr, &prev_tag);
 
             /* Invoke correct "high level" I/O routine */
@@ -936,7 +930,7 @@ H5D__ioinfo_init(size_t count, H5D_io_op_type_t op_type, H5D_dset_io_info_t *dse
 
     FUNC_ENTER_PACKAGE_NOERR
 
-    /* check args */
+    /* Check args */
     assert(count > 0);
     assert(dset_info);
     assert(dset_info[0].dset->oloc.file);
@@ -1057,7 +1051,7 @@ H5D__typeinfo_init(H5D_io_info_t *io_info, H5D_dset_io_info_t *dset_info, hid_t
 
     FUNC_ENTER_PACKAGE
 
-    /* check args */
+    /* Check args */
     assert(io_info);
     assert(dset_info);
 
@@ -1151,7 +1145,7 @@ done:
 /*-------------------------------------------------------------------------
  * Function:    H5D__typeinfo_init_phase2
  *
- * Purpose:     Continue initializing type info for all datasets after
+ * Purpose:     Continues initializing type info for all datasets after
  *              calculating the max type size across all datasets, and
  *              before final determination of collective/independent in
  *              H5D__ioinfo_adjust().  Currently just checks to see if
@@ -1169,7 +1163,7 @@ H5D__typeinfo_init_phase2(H5D_io_info_t *io_info)
 
     FUNC_ENTER_PACKAGE
 
-    /* check args */
+    /* Check args */
     assert(io_info);
 
     /* If selection I/O mode is default (auto), enable it here if the VFD supports it (it will be turned off
@@ -1238,7 +1232,7 @@ done:
 /*-------------------------------------------------------------------------
  * Function:    H5D__ioinfo_adjust
  *
- * Purpose:     Adjust operation's I/O info for any parallel I/O, also
+ * Purpose:     Adjusts operation's I/O info for any parallel I/O, also
  *              handle decision on selection I/O even in serial case
  *
  * Return:      Non-negative on success/Negative on failure
@@ -1253,10 +1247,10 @@ H5D__ioinfo_adjust(H5D_io_info_t *io_info)
 
     FUNC_ENTER_PACKAGE
 
-    /* check args */
+    /* Check args */
     assert(io_info);
 
-    /* check the first dset, should exist either single or multi dset cases */
+    /* Check the first dset, should exist either single or multi dset cases */
     assert(io_info->dsets_info[0].dset);
     dset0 = io_info->dsets_info[0].dset;
     assert(dset0->oloc.file);
@@ -1317,7 +1311,7 @@ H5D__ioinfo_adjust(H5D_io_info_t *io_info)
                     if (io_info->dsets_info[i].dset->shared->dcpl_cache.pline.nused > 0)
                         break;
 
-                /* If the above loop didn't complete at least one dataset has a filter */
+                /* If the above loop didn't complete, at least one dataset has a filter */
                 if (i < io_info->count) {
                     int comm_size = 0;
 
@@ -1363,9 +1357,9 @@ done:
 /*-------------------------------------------------------------------------
  * Function:    H5D__typeinfo_init_phase3
  *
- * Purpose:     Finish initializing type info for all datasets after
- *              calculating the max type size across all datasets.  And
- *              after final collective/independent determination in
+ * Purpose:     Finishes initializing type info for all datasets after
+ *              calculating the max type size across all datasets and
+ *              final collective/independent determination in
  *              H5D__ioinfo_adjust().
  *
  * Return:      Non-negative on success/Negative on failure
diff --git a/src/H5Dprivate.h b/src/H5Dprivate.h
index 118c6cd..fa8b077 100644
--- a/src/H5Dprivate.h
+++ b/src/H5Dprivate.h
@@ -78,15 +78,16 @@
 #define H5D_MPIO_LOCAL_NO_COLLECTIVE_CAUSE_NAME                                                              \
     "local_no_collective_cause" /* cause of broken collective I/O in each process */
 #define H5D_MPIO_GLOBAL_NO_COLLECTIVE_CAUSE_NAME                                                             \
-    "global_no_collective_cause"                         /* cause of broken collective I/O in all processes */
-#define H5D_XFER_EDC_NAME                   "err_detect" /* EDC */
-#define H5D_XFER_FILTER_CB_NAME             "filter_cb"  /* Filter callback function */
-#define H5D_XFER_CONV_CB_NAME               "type_conv_cb"          /* Type conversion callback function */
-#define H5D_XFER_XFORM_NAME                 "data_transform"        /* Data transform */
-#define H5D_XFER_DSET_IO_SEL_NAME           "dset_io_selection"     /* Dataset I/O selection */
-#define H5D_XFER_SELECTION_IO_MODE_NAME     "selection_io_mode"     /* Selection I/O mode */
-#define H5D_XFER_NO_SELECTION_IO_CAUSE_NAME "no_selection_io_cause" /* Cause for no selection I/O */
-#define H5D_XFER_MODIFY_WRITE_BUF_NAME      "modify_write_buf"      /* Modify write buffers */
+    "global_no_collective_cause" /* cause of broken collective I/O in all processes */
+#define H5D_XFER_EDC_NAME                      "err_detect"            /* EDC */
+#define H5D_XFER_FILTER_CB_NAME                "filter_cb"             /* Filter callback function */
+#define H5D_XFER_CONV_CB_NAME                  "type_conv_cb"          /* Type conversion callback function */
+#define H5D_XFER_XFORM_NAME                    "data_transform"        /* Data transform */
+#define H5D_XFER_DSET_IO_SEL_NAME              "dset_io_selection"     /* Dataset I/O selection */
+#define H5D_XFER_SELECTION_IO_MODE_NAME        "selection_io_mode"     /* Selection I/O mode */
+#define H5D_XFER_NO_SELECTION_IO_CAUSE_NAME    "no_selection_io_cause" /* Cause for no selection I/O */
+#define H5D_XFER_ACTUAL_SELECTION_IO_MODE_NAME "actual_selection_io_mode" /* Actual selection I/O mode */
+#define H5D_XFER_MODIFY_WRITE_BUF_NAME         "modify_write_buf"         /* Modify write buffers */
 #ifdef H5_HAVE_INSTRUMENTED_LIBRARY
 /* Collective chunk instrumentation properties */
 #define H5D_XFER_COLL_CHUNK_LINK_HARD_NAME        "coll_chunk_link_hard"
diff --git a/src/H5FDint.c b/src/H5FDint.c
index 082b602..5d3a802 100644
--- a/src/H5FDint.c
+++ b/src/H5FDint.c
@@ -212,8 +212,9 @@ done:
 herr_t
 H5FD_read(H5FD_t *file, H5FD_mem_t type, haddr_t addr, size_t size, void *buf /*out*/)
 {
-    hid_t  dxpl_id   = H5I_INVALID_HID; /* DXPL for operation */
-    herr_t ret_value = SUCCEED;         /* Return value */
+    hid_t    dxpl_id = H5I_INVALID_HID; /* DXPL for operation */
+    uint32_t actual_selection_io_mode;
+    herr_t   ret_value = SUCCEED; /* Return value */
 
     FUNC_ENTER_NOAPI(FAIL)
 
@@ -257,6 +258,13 @@ H5FD_read(H5FD_t *file, H5FD_mem_t type, haddr_t addr, size_t size, void *buf /*
     if ((file->cls->read)(file, type, dxpl_id, addr + file->base_addr, size, buf) < 0)
         HGOTO_ERROR(H5E_VFL, H5E_READERROR, FAIL, "driver read request failed");
 
+    /* Set actual selection I/O, if this is a raw data operation */
+    if (type == H5FD_MEM_DRAW) {
+        H5CX_get_actual_selection_io_mode(&actual_selection_io_mode);
+        actual_selection_io_mode |= H5D_SCALAR_IO;
+        H5CX_set_actual_selection_io_mode(actual_selection_io_mode);
+    }
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD_read() */
@@ -273,9 +281,10 @@ done:
 herr_t
 H5FD_write(H5FD_t *file, H5FD_mem_t type, haddr_t addr, size_t size, const void *buf)
 {
-    hid_t   dxpl_id;                 /* DXPL for operation */
-    haddr_t eoa       = HADDR_UNDEF; /* EOA for file */
-    herr_t  ret_value = SUCCEED;     /* Return value */
+    hid_t    dxpl_id;           /* DXPL for operation */
+    haddr_t  eoa = HADDR_UNDEF; /* EOA for file */
+    uint32_t actual_selection_io_mode;
+    herr_t   ret_value = SUCCEED; /* Return value */
 
     FUNC_ENTER_NOAPI(FAIL)
 
@@ -308,6 +317,13 @@ H5FD_write(H5FD_t *file, H5FD_mem_t type, haddr_t addr, size_t size, const void
     if ((file->cls->write)(file, type, dxpl_id, addr + file->base_addr, size, buf) < 0)
         HGOTO_ERROR(H5E_VFL, H5E_WRITEERROR, FAIL, "driver write request failed");
 
+    /* Set actual selection I/O, if this is a raw data operation */
+    if (type == H5FD_MEM_DRAW) {
+        H5CX_get_actual_selection_io_mode(&actual_selection_io_mode);
+        actual_selection_io_mode |= H5D_SCALAR_IO;
+        H5CX_set_actual_selection_io_mode(actual_selection_io_mode);
+    }
+
 done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD_write() */
@@ -360,6 +376,7 @@ H5FD_read_vector(H5FD_t *file, uint32_t count, H5FD_mem_t types[], haddr_t addrs
     size_t     size      = 0;
     H5FD_mem_t type      = H5FD_MEM_DEFAULT;
     hid_t      dxpl_id   = H5I_INVALID_HID; /* DXPL for operation */
+    hbool_t    is_raw    = FALSE;           /* Does this include raw data */
     herr_t     ret_value = SUCCEED;         /* Return value */
 
     FUNC_ENTER_NOAPI(FAIL)
@@ -441,6 +458,10 @@ H5FD_read_vector(H5FD_t *file, uint32_t count, H5FD_mem_t types[], haddr_t addrs
                 else {
 
                     type = types[i];
+
+                    /* Check for raw data operation */
+                    if (type == H5FD_MEM_DRAW)
+                        is_raw = TRUE;
                 }
             }
 
@@ -455,13 +476,27 @@ H5FD_read_vector(H5FD_t *file, uint32_t count, H5FD_mem_t types[], haddr_t addrs
                             (unsigned long long)eoa);
         }
     }
+    else
+        /* We must still check if this is a raw data read */
+        for (i = 0; i < count && types[i] != H5FD_MEM_NOLIST; i++)
+            if (types[i] == H5FD_MEM_DRAW) {
+                is_raw = true;
+                break;
+            }
 
     /* if the underlying VFD supports vector read, make the call */
     if (file->cls->read_vector) {
-
         if ((file->cls->read_vector)(file, dxpl_id, count, types, addrs, sizes, bufs) < 0)
-
             HGOTO_ERROR(H5E_VFL, H5E_READERROR, FAIL, "driver read vector request failed");
+
+        /* Set actual selection I/O mode, if this is a raw data operation */
+        if (is_raw) {
+            uint32_t actual_selection_io_mode;
+
+            H5CX_get_actual_selection_io_mode(&actual_selection_io_mode);
+            actual_selection_io_mode |= H5D_VECTOR_IO;
+            H5CX_set_actual_selection_io_mode(actual_selection_io_mode);
+        }
     }
     else {
 
@@ -471,6 +506,7 @@ H5FD_read_vector(H5FD_t *file, uint32_t count, H5FD_mem_t types[], haddr_t addrs
         extend_sizes = false;
         extend_types = false;
         uint32_t no_selection_io_cause;
+        uint32_t actual_selection_io_mode;
 
         for (i = 0; i < count; i++) {
 
@@ -512,6 +548,13 @@ H5FD_read_vector(H5FD_t *file, uint32_t count, H5FD_mem_t types[], haddr_t addrs
         H5CX_get_no_selection_io_cause(&no_selection_io_cause);
         no_selection_io_cause |= H5D_SEL_IO_NO_VECTOR_OR_SELECTION_IO_CB;
         H5CX_set_no_selection_io_cause(no_selection_io_cause);
+
+        /* Set actual selection I/O mode, if this is a raw data operation */
+        if (is_raw) {
+            H5CX_get_actual_selection_io_mode(&actual_selection_io_mode);
+            actual_selection_io_mode |= H5D_SCALAR_IO;
+            H5CX_set_actual_selection_io_mode(actual_selection_io_mode);
+        }
     }
 
 done:
@@ -575,6 +618,7 @@ H5FD_write_vector(H5FD_t *file, uint32_t count, H5FD_mem_t types[], haddr_t addr
     H5FD_mem_t type = H5FD_MEM_DEFAULT;
     hid_t      dxpl_id;                 /* DXPL for operation */
     haddr_t    eoa       = HADDR_UNDEF; /* EOA for file */
+    hbool_t    is_raw    = FALSE;       /* Does this include raw data */
     herr_t     ret_value = SUCCEED;     /* Return value */
 
     FUNC_ENTER_NOAPI(FAIL)
@@ -646,6 +690,10 @@ H5FD_write_vector(H5FD_t *file, uint32_t count, H5FD_mem_t types[], haddr_t addr
             else {
 
                 type = types[i];
+
+                /* Check for raw data operation */
+                if (type == H5FD_MEM_DRAW)
+                    is_raw = true;
             }
         }
 
@@ -663,10 +711,17 @@ H5FD_write_vector(H5FD_t *file, uint32_t count, H5FD_mem_t types[], haddr_t addr
 
     /* if the underlying VFD supports vector write, make the call */
     if (file->cls->write_vector) {
-
         if ((file->cls->write_vector)(file, dxpl_id, count, types, addrs, sizes, bufs) < 0)
-
             HGOTO_ERROR(H5E_VFL, H5E_WRITEERROR, FAIL, "driver write vector request failed");
+
+        /* Set actual selection I/O mode, if this is a raw data operation */
+        if (is_raw) {
+            uint32_t actual_selection_io_mode;
+
+            H5CX_get_actual_selection_io_mode(&actual_selection_io_mode);
+            actual_selection_io_mode |= H5D_VECTOR_IO;
+            H5CX_set_actual_selection_io_mode(actual_selection_io_mode);
+        }
     }
     else {
         /* otherwise, implement the vector write as a sequence of regular
@@ -675,6 +730,7 @@ H5FD_write_vector(H5FD_t *file, uint32_t count, H5FD_mem_t types[], haddr_t addr
         extend_sizes = false;
         extend_types = false;
         uint32_t no_selection_io_cause;
+        uint32_t actual_selection_io_mode;
 
         for (i = 0; i < count; i++) {
 
@@ -716,6 +772,13 @@ H5FD_write_vector(H5FD_t *file, uint32_t count, H5FD_mem_t types[], haddr_t addr
         H5CX_get_no_selection_io_cause(&no_selection_io_cause);
         no_selection_io_cause |= H5D_SEL_IO_NO_VECTOR_OR_SELECTION_IO_CB;
         H5CX_set_no_selection_io_cause(no_selection_io_cause);
+
+        /* Set actual selection I/O mode, if this is a raw data operation */
+        if (is_raw) {
+            H5CX_get_actual_selection_io_mode(&actual_selection_io_mode);
+            actual_selection_io_mode |= H5D_SCALAR_IO;
+            H5CX_set_actual_selection_io_mode(actual_selection_io_mode);
+        }
     }
 
 done:
@@ -996,18 +1059,35 @@ H5FD__read_selection_translate(uint32_t skip_vector_cb, H5FD_t *file, H5FD_mem_t
 
     /* Issue vector read call if appropriate */
     if (use_vector) {
+        uint32_t actual_selection_io_mode;
+
         H5_CHECK_OVERFLOW(vec_arr_nused, size_t, uint32_t);
         if ((file->cls->read_vector)(file, dxpl_id, (uint32_t)vec_arr_nused, types, addrs, sizes, vec_bufs) <
             0)
             HGOTO_ERROR(H5E_VFL, H5E_READERROR, FAIL, "driver read vector request failed");
+
+        /* Set actual selection I/O, if this is a raw data operation */
+        if (type == H5FD_MEM_DRAW && count > 0) {
+            H5CX_get_actual_selection_io_mode(&actual_selection_io_mode);
+            actual_selection_io_mode |= H5D_VECTOR_IO;
+            H5CX_set_actual_selection_io_mode(actual_selection_io_mode);
+        }
     }
-    else {
+    else if (count > 0) {
         uint32_t no_selection_io_cause;
+        uint32_t actual_selection_io_mode;
 
         /* Add H5D_SEL_IO_NO_VECTOR_OR_SELECTION_IO_CB to no selection I/O cause */
         H5CX_get_no_selection_io_cause(&no_selection_io_cause);
         no_selection_io_cause |= H5D_SEL_IO_NO_VECTOR_OR_SELECTION_IO_CB;
         H5CX_set_no_selection_io_cause(no_selection_io_cause);
+
+        /* Set actual selection I/O, if this is a raw data operation */
+        if (type == H5FD_MEM_DRAW) {
+            H5CX_get_actual_selection_io_mode(&actual_selection_io_mode);
+            actual_selection_io_mode |= H5D_SCALAR_IO;
+            H5CX_set_actual_selection_io_mode(actual_selection_io_mode);
+        }
     }
 
 done:
@@ -1161,6 +1241,8 @@ H5FD_read_selection(H5FD_t *file, H5FD_mem_t type, uint32_t count, H5S_t **mem_s
 
     /* if the underlying VFD supports selection read, make the call */
     if (file->cls->read_selection) {
+        uint32_t actual_selection_io_mode;
+
         /* Allocate array of space IDs if necessary, otherwise use local
          * buffers */
         if (count > sizeof(mem_space_ids_local) / sizeof(mem_space_ids_local[0])) {
@@ -1186,6 +1268,13 @@ H5FD_read_selection(H5FD_t *file, H5FD_mem_t type, uint32_t count, H5S_t **mem_s
         if ((file->cls->read_selection)(file, type, dxpl_id, count, mem_space_ids, file_space_ids, offsets,
                                         element_sizes, bufs) < 0)
             HGOTO_ERROR(H5E_VFL, H5E_READERROR, FAIL, "driver read selection request failed");
+
+        /* Set actual selection I/O, if this is a raw data operation */
+        if (type == H5FD_MEM_DRAW) {
+            H5CX_get_actual_selection_io_mode(&actual_selection_io_mode);
+            actual_selection_io_mode |= H5D_SELECTION_IO;
+            H5CX_set_actual_selection_io_mode(actual_selection_io_mode);
+        }
     }
     else
         /* Otherwise, implement the selection read as a sequence of regular
@@ -1337,9 +1426,18 @@ H5FD_read_selection_id(uint32_t skip_cb, H5FD_t *file, H5FD_mem_t type, uint32_t
 
     /* if the underlying VFD supports selection read, make the call */
     if (!skip_selection_cb && file->cls->read_selection) {
+        uint32_t actual_selection_io_mode;
+
         if ((file->cls->read_selection)(file, type, dxpl_id, count, mem_space_ids, file_space_ids, offsets,
                                         element_sizes, bufs) < 0)
             HGOTO_ERROR(H5E_VFL, H5E_READERROR, FAIL, "driver read selection request failed");
+
+        /* Set actual selection I/O, if this is a raw data operation */
+        if (type == H5FD_MEM_DRAW) {
+            H5CX_get_actual_selection_io_mode(&actual_selection_io_mode);
+            actual_selection_io_mode |= H5D_SELECTION_IO;
+            H5CX_set_actual_selection_io_mode(actual_selection_io_mode);
+        }
     }
     else {
         /* Otherwise, implement the selection read as a sequence of regular
@@ -1653,18 +1751,35 @@ H5FD__write_selection_translate(uint32_t skip_vector_cb, H5FD_t *file, H5FD_mem_
 
     /* Issue vector write call if appropriate */
     if (use_vector) {
+        uint32_t actual_selection_io_mode;
+
         H5_CHECK_OVERFLOW(vec_arr_nused, size_t, uint32_t);
         if ((file->cls->write_vector)(file, dxpl_id, (uint32_t)vec_arr_nused, types, addrs, sizes, vec_bufs) <
             0)
             HGOTO_ERROR(H5E_VFL, H5E_WRITEERROR, FAIL, "driver write vector request failed");
+
+        /* Set actual selection I/O, if this is a raw data operation */
+        if (type == H5FD_MEM_DRAW && count > 0) {
+            H5CX_get_actual_selection_io_mode(&actual_selection_io_mode);
+            actual_selection_io_mode |= H5D_VECTOR_IO;
+            H5CX_set_actual_selection_io_mode(actual_selection_io_mode);
+        }
     }
-    else {
+    else if (count > 0) {
         uint32_t no_selection_io_cause;
+        uint32_t actual_selection_io_mode;
 
         /* Add H5D_SEL_IO_NO_VECTOR_OR_SELECTION_IO_CB to no selection I/O cause */
         H5CX_get_no_selection_io_cause(&no_selection_io_cause);
         no_selection_io_cause |= H5D_SEL_IO_NO_VECTOR_OR_SELECTION_IO_CB;
         H5CX_set_no_selection_io_cause(no_selection_io_cause);
+
+        /* Set actual selection I/O, if this is a raw data operation */
+        if (type == H5FD_MEM_DRAW) {
+            H5CX_get_actual_selection_io_mode(&actual_selection_io_mode);
+            actual_selection_io_mode |= H5D_SCALAR_IO;
+            H5CX_set_actual_selection_io_mode(actual_selection_io_mode);
+        }
     }
 
 done:
@@ -1810,6 +1925,8 @@ H5FD_write_selection(H5FD_t *file, H5FD_mem_t type, uint32_t count, H5S_t **mem_
 
     /* if the underlying VFD supports selection write, make the call */
     if (file->cls->write_selection) {
+        uint32_t actual_selection_io_mode;
+
         /* Allocate array of space IDs if necessary, otherwise use local
          * buffers */
         if (count > sizeof(mem_space_ids_local) / sizeof(mem_space_ids_local[0])) {
@@ -1835,6 +1952,13 @@ H5FD_write_selection(H5FD_t *file, H5FD_mem_t type, uint32_t count, H5S_t **mem_
         if ((file->cls->write_selection)(file, type, dxpl_id, count, mem_space_ids, file_space_ids, offsets,
                                          element_sizes, bufs) < 0)
             HGOTO_ERROR(H5E_VFL, H5E_WRITEERROR, FAIL, "driver write selection request failed");
+
+        /* Set actual selection I/O, if this is a raw data operation */
+        if (type == H5FD_MEM_DRAW) {
+            H5CX_get_actual_selection_io_mode(&actual_selection_io_mode);
+            actual_selection_io_mode |= H5D_SELECTION_IO;
+            H5CX_set_actual_selection_io_mode(actual_selection_io_mode);
+        }
     }
     else
         /* Otherwise, implement the selection write as a sequence of regular
@@ -1979,9 +2103,18 @@ H5FD_write_selection_id(uint32_t skip_cb, H5FD_t *file, H5FD_mem_t type, uint32_
 
     /* if the underlying VFD supports selection write, make the call */
     if (!skip_selection_cb && file->cls->write_selection) {
+        uint32_t actual_selection_io_mode;
+
         if ((file->cls->write_selection)(file, type, dxpl_id, count, mem_space_ids, file_space_ids, offsets,
                                          element_sizes, bufs) < 0)
             HGOTO_ERROR(H5E_VFL, H5E_WRITEERROR, FAIL, "driver write selection request failed");
+
+        /* Set actual selection I/O, if this is a raw data operation */
+        if (type == H5FD_MEM_DRAW) {
+            H5CX_get_actual_selection_io_mode(&actual_selection_io_mode);
+            actual_selection_io_mode |= H5D_SELECTION_IO;
+            H5CX_set_actual_selection_io_mode(actual_selection_io_mode);
+        }
     }
     else {
         /* Otherwise, implement the selection write as a sequence of regular
diff --git a/src/H5M.c b/src/H5M.c
index e2fd202..f59e02f 100644
--- a/src/H5M.c
+++ b/src/H5M.c
@@ -893,9 +893,6 @@ H5Mget_count(hid_t map_id, hsize_t *count /*out*/, hid_t dxpl_id)
     else if (true != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms");
 
-    /* Set DXPL for operation */
-    H5CX_set_dxpl(dxpl_id);
-
     /* Set up VOL callback arguments */
     map_args.get.get_type             = H5VL_MAP_GET_COUNT;
     map_args.get.args.get_count.count = 0;
@@ -952,9 +949,6 @@ H5M__put_api_common(hid_t map_id, hid_t key_mem_type_id, const void *key, hid_t
     else if (true != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms");
 
-    /* Set DXPL for operation */
-    H5CX_set_dxpl(dxpl_id);
-
     /* Set up VOL callback arguments */
     map_args.put.key_mem_type_id   = key_mem_type_id;
     map_args.put.key               = key;
@@ -1087,9 +1081,6 @@ H5M__get_api_common(hid_t map_id, hid_t key_mem_type_id, const void *key, hid_t
     else if (true != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms");
 
-    /* Set DXPL for operation */
-    H5CX_set_dxpl(dxpl_id);
-
     /* Set up VOL callback arguments */
     map_args.get_val.key_mem_type_id   = key_mem_type_id;
     map_args.get_val.key               = key;
@@ -1225,9 +1216,6 @@ H5Mexists(hid_t map_id, hid_t key_mem_type_id, const void *key, hbool_t *exists,
     else if (true != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms");
 
-    /* Set DXPL for operation */
-    H5CX_set_dxpl(dxpl_id);
-
     /* Set up VOL callback arguments */
     map_args.exists.key_mem_type_id = key_mem_type_id;
     map_args.exists.key             = key;
@@ -1305,9 +1293,6 @@ H5Miterate(hid_t map_id, hsize_t *idx, hid_t key_mem_type_id, H5M_iterate_t op,
     else if (true != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms");
 
-    /* Set DXPL for operation */
-    H5CX_set_dxpl(dxpl_id);
-
     /* Set up VOL callback arguments */
     map_args.specific.specific_type                    = H5VL_MAP_ITER;
     map_args.specific.args.iterate.loc_params.type     = H5VL_OBJECT_BY_SELF;
@@ -1394,9 +1379,6 @@ H5Miterate_by_name(hid_t loc_id, const char *map_name, hsize_t *idx, hid_t key_m
     else if (true != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms");
 
-    /* Set DXPL for operation */
-    H5CX_set_dxpl(dxpl_id);
-
     /* Set up VOL callback arguments */
     map_args.specific.specific_type                                        = H5VL_MAP_ITER;
     map_args.specific.args.iterate.loc_params.type                         = H5VL_OBJECT_BY_NAME;
@@ -1462,9 +1444,6 @@ H5Mdelete(hid_t map_id, hid_t key_mem_type_id, const void *key, hid_t dxpl_id)
     else if (true != H5P_isa_class(dxpl_id, H5P_DATASET_XFER))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms");
 
-    /* Set DXPL for operation */
-    H5CX_set_dxpl(dxpl_id);
-
     /* Set up VOL callback arguments */
     map_args.specific.specific_type                = H5VL_MAP_DELETE;
     map_args.specific.args.del.loc_params.type     = H5VL_OBJECT_BY_SELF;
diff --git a/src/H5Pdxpl.c b/src/H5Pdxpl.c
index b6130f5..9adb2d6 100644
--- a/src/H5Pdxpl.c
+++ b/src/H5Pdxpl.c
@@ -175,6 +175,9 @@
 /* Definitions for cause of no selection I/O property */
 #define H5D_XFER_NO_SELECTION_IO_CAUSE_SIZE sizeof(uint32_t)
 #define H5D_XFER_NO_SELECTION_IO_CAUSE_DEF  0
+/* Definitions for actual selection I/O mode property */
+#define H5D_XFER_ACTUAL_SELECTION_IO_MODE_SIZE sizeof(uint32_t)
+#define H5D_XFER_ACTUAL_SELECTION_IO_MODE_DEF  0
 /* Definitions for modify write buffer property */
 #define H5D_XFER_MODIFY_WRITE_BUF_SIZE sizeof(bool)
 #define H5D_XFER_MODIFY_WRITE_BUF_DEF  false
@@ -295,7 +298,8 @@ static const H5S_t *H5D_def_dset_io_sel_g =
     H5D_XFER_DSET_IO_SEL_DEF; /* Default value for dataset I/O selection */
 static const H5D_selection_io_mode_t H5D_def_selection_io_mode_g     = H5D_XFER_SELECTION_IO_MODE_DEF;
 static const uint32_t                H5D_def_no_selection_io_cause_g = H5D_XFER_NO_SELECTION_IO_CAUSE_DEF;
-static const bool                    H5D_def_modify_write_buf_g      = H5D_XFER_MODIFY_WRITE_BUF_DEF;
+static const uint32_t H5D_def_actual_selection_io_mode_g             = H5D_XFER_ACTUAL_SELECTION_IO_MODE_DEF;
+static const bool     H5D_def_modify_write_buf_g                     = H5D_XFER_MODIFY_WRITE_BUF_DEF;
 
 /*-------------------------------------------------------------------------
  * Function:    H5P__dxfr_reg_prop
@@ -470,6 +474,13 @@ H5P__dxfr_reg_prop(H5P_genclass_t *pclass)
                            NULL) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class");
 
+    /* Register the actual selection I/O mode property */
+    /* (Note: this property should not have an encode/decode callback) */
+    if (H5P__register_real(pclass, H5D_XFER_ACTUAL_SELECTION_IO_MODE_NAME,
+                           H5D_XFER_ACTUAL_SELECTION_IO_MODE_SIZE, &H5D_def_actual_selection_io_mode_g, NULL,
+                           NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, FAIL, "can't insert property into class");
+
     /* Register the modify write buffer property */
     if (H5P__register_real(pclass, H5D_XFER_MODIFY_WRITE_BUF_NAME, H5D_XFER_MODIFY_WRITE_BUF_SIZE,
                            &H5D_def_modify_write_buf_g, NULL, NULL, NULL, H5D_XFER_MODIFY_WRITE_BUF_ENC,
@@ -2457,6 +2468,39 @@ done:
 } /* end H5Pget_no_selection_io_cause() */
 
 /*-------------------------------------------------------------------------
+ * Function:	H5Pget_actual_selection_io_mode
+ *
+ * Purpose:	    Retrieves actual selection I/O mode
+ *
+ * Return:	    Non-negative on success/Negative on failure
+ *
+ * Programmer:	Vailin Choi
+ *              April 27, 2023
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pget_actual_selection_io_mode(hid_t plist_id, uint32_t *actual_selection_io_mode /*out*/)
+{
+    H5P_genplist_t *plist;
+    herr_t          ret_value = SUCCEED; /* return value */
+
+    FUNC_ENTER_API(FAIL)
+    H5TRACE2("e", "ix", plist_id, actual_selection_io_mode);
+
+    /* Get the plist structure */
+    if (NULL == (plist = H5P_object_verify(plist_id, H5P_DATASET_XFER)))
+        HGOTO_ERROR(H5E_ID, H5E_BADID, FAIL, "can't find object for ID");
+
+    /* Return values */
+    if (actual_selection_io_mode)
+        if (H5P_get(plist, H5D_XFER_ACTUAL_SELECTION_IO_MODE_NAME, actual_selection_io_mode) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get actual_selection_io_mode value");
+
+done:
+    FUNC_LEAVE_API(ret_value)
+} /* end H5Pget_actual_selection_io_mode() */
+
+/*-------------------------------------------------------------------------
  * Function:    H5P__dxfr_modify_write_buf_enc
  *
  * Purpose:     Callback routine which is called whenever the modify write
diff --git a/src/H5Ppublic.h b/src/H5Ppublic.h
index a58d97f..64ccb77 100644
--- a/src/H5Ppublic.h
+++ b/src/H5Ppublic.h
@@ -420,6 +420,13 @@ typedef enum H5D_selection_io_mode_t {
 } H5D_selection_io_mode_t;
 //! <!--[H5D_selection_io_mode_t_snip] -->
 
+/**
+ * Causes for H5Pget_actual_selection_io_mode() property
+ */
+#define H5D_SCALAR_IO    (0x0001u) /**< Scalar (or legacy MPIO) I/O was performed */
+#define H5D_VECTOR_IO    (0x0002u) /**< Vector I/O was performed */
+#define H5D_SELECTION_IO (0x0004u) /**< Selection I/O was performed */
+
 /********************/
 /* Public Variables */
 /********************/
@@ -4830,9 +4837,8 @@ H5_DLL herr_t H5Pset_gc_references(hid_t fapl_id, unsigned gc_ref);
  *          enumerated value in #H5F_libver_t, indicating that this is
  *          currently the latest format available.
  *
- *          The library supports the following five pairs of
- *          (\p low, \p high) combinations as derived from the values
- *          in #H5F_libver_t:
+ *          The library supports the following pairs of (\p low, \p high)
+ *          combinations as derived from the values in #H5F_libver_t:
  *
  *          <table>
  *           <tr>
@@ -4859,13 +4865,38 @@ H5_DLL herr_t H5Pset_gc_references(hid_t fapl_id, unsigned gc_ref);
  *             \li The library will create objects with the earliest possible
  *                 format versions.
  *             \li The library will allow objects to be created with the latest
- *                 format versions available to library release 1.10.x.
- *                 Since 1.10.x is also #H5F_LIBVER_LATEST, there is no upper
- *                 limit on the format versions to use.  For example, if a newer
- *                 format version is required to support a feature e.g. virtual
- *                 dataset, this setting will allow the object to be created.
- *             \li This is the library default setting and provides the greatest
- *                 format compatibility.
+ *                 format versions available to library release 1.10.x.  Note
+ *                 that as 1.10.11 is the last release of the 1.10 series.
+ *             \li API calls that create objects or features that are
+ *                 available to versions of the library greater than 1.10.x
+ *                 release will fail.
+ *            </td>
+ *           </tr>
+ *           <tr>
+ *            <td>\p low=#H5F_LIBVER_EARLIEST<br />
+ *                \p high=#H5F_LIBVER_V112</td>
+ *            <td>
+ *             \li The library will create objects with the earliest possible
+ *                 format versions.
+ *             \li The library will allow objects to be created with the latest
+ *                 format versions available to library release 1.12.x.  Note
+ *                 that as 1.12.3 is the last release of the 1.12 series.
+ *             \li API calls that create objects or features that are
+ *                 available to versions of the library greater than 1.12.x
+ *                 release will fail.
+ *            </td>
+ *           </tr>
+ *           <tr>
+ *            <td>\p low=#H5F_LIBVER_EARLIEST<br />
+ *                \p high=#H5F_LIBVER_V114</td>
+ *            <td>
+ *             \li The library will create objects with the earliest possible
+ *                 format versions.
+ *             \li The library will allow objects to be created with the latest
+ *                 format versions available to library release 1.14.x.
+ *             \li API calls that create objects or features that are
+ *                 available to versions of the library greater than 1.14.x
+ *                 release will fail.
  *            </td>
  *           </tr>
  *           <tr>
@@ -4887,12 +4918,39 @@ H5_DLL herr_t H5Pset_gc_references(hid_t fapl_id, unsigned gc_ref);
  *              \li The library will create objects with the latest format
  *                  versions available to library release 1.8.x.
  *              \li The library will allow objects to be created with the latest
- *                  format versions available to library release 1.10.x.
- *                  Since 1.10.x is also #H5F_LIBVER_LATEST, there is no upper
- *                  limit on the format versions to use.  For example, if a
- *                  newer format version is required to support a feature e.g.
- *                  virtual dataset, this setting will allow the object to be
- *                  created.
+ *                  format versions available to library release 1.10.x.  Note
+ *                  that 1.10.11 is the last release of the 1.10 series.
+ *              \li API calls that create objects or features that are
+ *                  available to versions of the library greater than 1.10.x
+ *                  release will fail.
+ *              \li Earlier versions of the library may not be able to access
+ *                  objects created with this setting.</td>
+ *           </tr>
+ *           <tr>
+ *            <td>\p low=#H5F_LIBVER_V18<br />
+ *                \p high=#H5F_LIBVER_V112</td>
+ *            <td>
+ *              \li The library will create objects with the latest format
+ *                  versions available to library release 1.8.x.
+ *              \li The library will allow objects to be created with the latest
+ *                  format versions available to library release 1.12.x.
+ *              \li API calls that create objects or features that are
+ *                  available to versions of the library greater than 1.12.x
+ *                  release will fail.
+ *              \li Earlier versions of the library may not be able to access
+ *                  objects created with this setting.</td>
+ *           </tr>
+ *           <tr>
+ *            <td>\p low=#H5F_LIBVER_V18<br />
+ *                \p high=#H5F_LIBVER_V114</td>
+ *            <td>
+ *              \li The library will create objects with the latest format
+ *                  versions available to library release 1.8.x.
+ *              \li The library will allow objects to be created with the latest
+ *                  format versions available to library release 1.14.x.
+ *              \li API calls that create objects or features that are
+ *                  available to versions of the library greater than 1.14.x
+ *                  release will fail.
  *              \li Earlier versions of the library may not be able to access
  *                  objects created with this setting.</td>
  *           </tr>
@@ -4904,22 +4962,115 @@ H5_DLL herr_t H5Pset_gc_references(hid_t fapl_id, unsigned gc_ref);
  *              \li The library will create objects with the latest format
  *                  versions available to library release 1.10.x.
  *              \li The library will allow objects to be created with the latest
- *                  format versions available to library release 1.10.x.
- *                  Since 1.10.x is also #H5F_LIBVER_LATEST, there is no upper
- *                  limit on the format versions to use. For example, if a
- *                  newer format version is required to support a feature e.g.
- *                  virtual dataset, this setting will allow the object to be
- *                  created.
- *              \li This setting allows users to take advantage of the latest
- *                  features and performance enhancements in the library.
- *                  However, objects written with this setting may be
+ *                  format versions available to library release 1.10.x.  Note
+ *                  that 1.10.11 is the last release of the 1.10 series.
+ *              \li The objects written with this setting may be
+ *                  accessible to a smaller range of library versions than
+ *                  would be the case if low is set to #H5F_LIBVER_EARLIEST.
+ *              \li API calls that create objects or features that are available
+ *                  to versions of the library greater than 1.10.x release will
+ *                  fail.
+ *              \li Earlier versions of the library may not be able to access
+ *                  objects created with this setting.</td>
+ *            </td>
+ *           </tr>
+ *           <tr>
+ *            <td>\p low=#H5F_LIBVER_V110<br />
+ *                \p high=#H5F_LIBVER_V112
+ *             </td>
+ *             <td>
+ *              \li The library will create objects with the latest format
+ *                  versions available to library release 1.10.x.
+ *              \li The library will allow objects to be created with the latest
+ *                  format versions available to library release 1.12.x.
+ *              \li The objects written with this setting may be
  *                  accessible to a smaller range of library versions than
  *                  would be the case if low is set to #H5F_LIBVER_EARLIEST.
+ *              \li API calls that create objects or features that are available
+ *                  to versions of the library greater than 1.12.x release will
+ *                  fail.
  *              \li Earlier versions of the library may not be able to access
- *                  objects created with this
- * setting.
+ *                  objects created with this setting.</td>
  *            </td>
  *           </tr>
+ *           <tr>
+ *            <td>\p low=#H5F_LIBVER_V110<br />
+ *                \p high=#H5F_LIBVER_V114
+ *             </td>
+ *             <td>
+ *              \li The library will create objects with the latest format
+ *                  versions available to library release 1.10.x.
+ *              \li The library will allow objects to be created with the latest
+ *                  format versions available to library release 1.14.x.
+ *              \li The objects written with this setting may be
+ *                  accessible to a smaller range of library versions than
+ *                  would be the case if low is set to #H5F_LIBVER_EARLIEST.
+ *              \li API calls that create objects or features that are available
+ *                  to versions of the library greater than 1.14.x release will
+ *                  fail.
+ *              \li Earlier versions of the library may not be able to access
+ *                  objects created with this setting.</td>
+ *            </td>
+ *           </tr>
+ *           <tr>
+ *            <td>\p low=#H5F_LIBVER_V112<br />
+ *                \p high=#H5F_LIBVER_V112
+ *             </td>
+ *             <td>
+ *              \li The library will create objects with the latest format
+ *                  versions available to library release 1.12.x.
+ *              \li The library will allow objects to be created with the latest
+ *                  format versions available to library release 1.12.x.
+ *              \li The objects written with this setting may be
+ *                  accessible to a smaller range of library versions than
+ *                  would be the case if low is set to #H5F_LIBVER_EARLIEST.
+ *              \li API calls that create objects or features that are available
+ *                  to versions of the library greater than 1.12.x release will
+ *                  fail.
+ *              \li Earlier versions of the library may not be able to access
+ *                  objects created with this setting.</td>
+ *            </td>
+ *           </tr>
+ *           <tr>
+ *            <td>\p low=#H5F_LIBVER_V112<br />
+ *                \p high=#H5F_LIBVER_V114
+ *             </td>
+ *             <td>
+ *              \li The library will create objects with the latest format
+ *                  versions available to library release 1.12.x.
+ *              \li The library will allow objects to be created with the latest
+ *                  format versions available to library release 1.14.x.
+ *              \li The objects written with this setting may be
+ *                  accessible to a smaller range of library versions than
+ *                  would be the case if low is set to #H5F_LIBVER_EARLIEST.
+ *              \li API calls that create objects or features that are available
+ *                  to versions of the library greater than 1.14.x release will
+ *                  fail.
+ *              \li Earlier versions of the library may not be able to access
+ *                  objects created with this setting.</td>
+ *            </td>
+ *           </tr>
+ *           </tr>
+ *           <tr>
+ *            <td>\p low=#H5F_LIBVER_V114<br />
+ *                \p high=#H5F_LIBVER_V114
+ *             </td>
+ *             <td>
+ *              \li The library will create objects with the latest format
+ *                  versions available to library release 1.14.x.
+ *              \li The library will allow objects to be created with the latest
+ *                  format versions available to library release 1.14.x.
+ *              \li The objects written with this setting may be
+ *                  accessible to a smaller range of library versions than
+ *                  would be the case if low is set to #H5F_LIBVER_EARLIEST.
+ *              \li API calls that create objects or features that are available
+ *                  to versions of the library greater than 1.14.x release will
+ *                  fail.
+ *              \li Earlier versions of the library may not be able to access
+ *                  objects created with this setting.</td>
+ *            </td>
+ *           </tr>
+ *           </tr>
  *          </table>
  *
  * \version 1.10.2 #H5F_LIBVER_V18 added to the enumerated defines in
@@ -5811,7 +5962,7 @@ H5_DLL int H5Pget_external_count(hid_t plist_id);
  * \note H5Pget_fill_time() is designed to work in coordination with the
  *       dataset fill value and dataset storage allocation time properties,
  *       retrieved with the functions H5Pget_fill_value() and
- *       H5Pget_alloc_time().
+ *       H5Pget_alloc_time().type == H5FD_MEM_DRAW
  *
  * \since 1.6.0
  *
@@ -8300,6 +8451,61 @@ H5_DLL herr_t H5Pget_selection_io(hid_t plist_id, H5D_selection_io_mode_t *selec
 H5_DLL herr_t H5Pget_no_selection_io_cause(hid_t plist_id, uint32_t *no_selection_io_cause);
 
 /**
+ * \ingroup DXPL
+ *
+ * \brief Retrieves the type(s) of I/O that HDF5 actually performed on raw data
+ *        during the last I/O call
+ *
+ * \dxpl_id{plist_id}
+ * \param[out] actual_selection_io_mode A bitwise set value indicating the
+ *                                      type(s) of I/O performed
+ * \return \herr_t
+ *
+ * \par Motivation:
+ *      A user can request selection I/O to be performed via a data transfer
+ *      property list (DXPL).  This can be used to enable collective I/O with
+ *      type conversion, or with custom VFDs that support vector or selection
+ *      I/O.  However, there are conditions that can cause HDF5 to forgo
+ *      selection or vector I/O and perform legacy (scalar) I/O instead.
+ *      This function allows the user to determine which type or types of
+ *      I/O were actually performed.
+ *
+ * \details H5Pget_actual_selection_io_mode() allows the user to determine which
+ *          type(s) of I/O were actually performed on raw data during the last
+ *          I/O operation which used \p plist_id.  This property is set after
+ *          all I/O is completed; if I/O fails, it will not be set.
+ *
+ *          H5Pget_no_selection_io_cause() can be used to determine the reason
+ *          why selection or vector I/O was not performed.
+ *
+ *          Valid bitflags returned in \p actual_selection_io_mode are listed
+ *          as follows.
+ *
+ *          - #H5D_SCALAR_IO
+ *          Scalar (or legacy MPIO) I/O was performed
+ *          - #H5D_VECTOR_IO
+ *          Vector I/O was performed
+ *          - #H5D_SELECTION_IO
+ *          Selection I/O was performed
+ *
+ *          0 or more of these can be present in \p actual_selection_io_mode in
+ *          a bitwise fashion, since a single operation can trigger multiple
+ *          instances of I/O, possibly with different types.  A value of \p 0
+ *          indicates no raw data I/O was performed during the operation.
+ *
+ *          Be aware that this function will only include raw data I/O performed
+ *          to/from disk as part of the last I/O operation.  Any metadata
+ *          I/O, including attribute and compact dataset I/O, is disregarded.
+ *          It is also possible that data was cached in the dataset chunk cache
+ *          or sieve buffer, which may prevent I/O from hitting the disk, and
+ *          thereby prevent it from being counted by this function.
+ *
+ * \since 1.14.3
+ *
+ */
+H5_DLL herr_t H5Pget_actual_selection_io_mode(hid_t plist_id, uint32_t *actual_selection_io_mode);
+
+/**
  *
  * \ingroup DXPL
  *