Initial 2GB port from develop to the 1_12 branch

5 files changed, 297 insertions, 187 deletions

diff --git a/src/H5FDmpio.c b/src/H5FDmpio.c
index 71e9fe1..11f0411 100644
--- a/src/H5FDmpio.c
+++ b/src/H5FDmpio.c
@@ -22,15 +22,15 @@
 #include "H5FDdrvr_module.h" /* This source code file is part of the H5FD driver module */
 
 
-#include "H5private.h"		/* Generic Functions			*/
+#include "H5private.h"          /* Generic Functions                    */
 #include "H5CXprivate.h"        /* API Contexts                         */
-#include "H5Dprivate.h"		/* Dataset functions			*/
-#include "H5Eprivate.h"		/* Error handling		  	*/
-#include "H5Fprivate.h"		/* File access				*/
-#include "H5FDprivate.h"	/* File drivers				*/
-#include "H5FDmpi.h"            /* MPI-based file drivers		*/
-#include "H5Iprivate.h"		/* IDs			  		*/
-#include "H5MMprivate.h"	/* Memory management			*/
+#include "H5Dprivate.h"         /* Dataset functions                    */
+#include "H5Eprivate.h"         /* Error handling                       */
+#include "H5Fprivate.h"         /* File access                          */
+#include "H5FDprivate.h"        /* File drivers                         */
+#include "H5FDmpi.h"            /* MPI-based file drivers               */
+#include "H5Iprivate.h"         /* IDs                                  */
+#include "H5MMprivate.h"        /* Memory management                    */
 #include "H5Pprivate.h"         /* Property lists                       */
 
 #ifdef H5_HAVE_PARALLEL
@@ -1324,6 +1324,7 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5FD__mpio_read() */
 
+
 
 /*-------------------------------------------------------------------------
  * Function:    H5FD__mpio_write
@@ -1366,6 +1367,7 @@ H5FD__mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id,
 #endif
     int                         size_i;
     hbool_t                     use_view_this_time = FALSE;
+    hbool_t                     derived_type = FALSE;
     H5FD_mpio_xfer_t            xfer_mode;   /* I/O transfer mode */
     herr_t                      ret_value = SUCCEED;
 
@@ -1391,8 +1393,6 @@ H5FD__mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id,
     if(H5FD_mpi_haddr_to_MPIOff(addr, &mpi_off) < 0)
         HGOTO_ERROR(H5E_INTERNAL, H5E_BADRANGE, FAIL, "can't convert from haddr to MPI off")
     size_i = (int)size;
-    if((hsize_t)size_i != size)
-        HGOTO_ERROR(H5E_INTERNAL, H5E_BADRANGE, FAIL, "can't convert from size to size_i")
 
 #ifdef H5FDmpio_DEBUG
     if(H5FD_mpio_Debug[(int)'w'])
@@ -1430,6 +1430,20 @@ H5FD__mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id,
          */
         mpi_off = 0;
     } /* end if */
+    else if(size != (hsize_t)size_i) {
+        /* If HERE, then we need to work around the integer size limit
+         * of 2GB. The input size_t size variable cannot fit into an integer,
+         * but we can get around that limitation by creating a different datatype
+         * and then setting the integer size (or element count) to 1 when using
+         * the derived_type.
+         */
+
+       if (H5_mpio_create_large_type(size, 0, MPI_BYTE, &buf_type) < 0)
+            HGOTO_ERROR(H5E_INTERNAL, H5E_CANTGET, FAIL, "can't create MPI-I/O datatype")
+
+        derived_type = TRUE;
+        size_i = 1;
+    }
 
     /* Write the data. */
     if(use_view_this_time) {
@@ -1506,6 +1520,9 @@ H5FD__mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t H5_ATTR_UNUSED dxpl_id,
         file->local_eof = addr + (haddr_t)bytes_written;
 
 done:
+    if(derived_type) {
+        MPI_Type_free(&buf_type);
+    }
 #ifdef H5FDmpio_DEBUG
     if(H5FD_mpio_Debug[(int)'t'])
         HDfprintf(stdout, "%s: Leaving, proc %d: ret_value = %d\n", FUNC, file->mpi_rank, ret_value );
diff --git a/src/H5Smpio.c b/src/H5Smpio.c
index aeec566..9112d24 100644
--- a/src/H5Smpio.c
+++ b/src/H5Smpio.c
@@ -42,11 +42,10 @@
 /* Local Macros */
 /****************/
 #define H5S_MPIO_INITIAL_ALLOC_COUNT    256
-#define TWO_GIG_LIMIT                   2147483648
-#ifndef H5S_MAX_MPI_COUNT
-#define H5S_MAX_MPI_COUNT               536870911  /* (2^29)-1  */
-#endif
 
+/*******************/
+/* Local Variables */
+/*******************/
 
 /******************/
 /* Local Typedefs */
@@ -88,8 +87,6 @@ static herr_t H5S__release_datatype(H5S_mpio_mpitype_list_t *type_list);
 static herr_t H5S__obtain_datatype(H5S_hyper_span_info_t *spans, const hsize_t *down,
     size_t elmt_size, const MPI_Datatype *elmt_type, MPI_Datatype *span_type,
     H5S_mpio_mpitype_list_t *type_list, uint64_t op_gen);
-static herr_t H5S__mpio_create_large_type(hsize_t num_elements, MPI_Aint stride_bytes,
-    MPI_Datatype old_type, MPI_Datatype *new_type);
 
 
 /*****************************/
@@ -102,40 +99,9 @@ static herr_t H5S__mpio_create_large_type(hsize_t num_elements, MPI_Aint stride_
 /*********************/
 
 
-/*******************/
-/* Local Variables */
-/*******************/
-static hsize_t bigio_count = H5S_MAX_MPI_COUNT;
-
 /* Declare a free list to manage the H5S_mpio_mpitype_node_t struct */
 H5FL_DEFINE_STATIC(H5S_mpio_mpitype_node_t);
 
-
-
-/*-------------------------------------------------------------------------
- * Function:  H5S_mpio_set_bigio_count
- *
- * Purpose:   Allow us to programatically change the switch point
- *            when we utilize derived datatypes.  This is of
- *            particular interest for allowing nightly testing
- *
- * Return:    The current/previous value of bigio_count.
- *
- * Programmer: Richard Warren,  March 10, 2017
- *
- *-------------------------------------------------------------------------
- */
-hsize_t
-H5S_mpio_set_bigio_count(hsize_t new_count)
-{
-    hsize_t orig_count = bigio_count;
-
-    if((new_count > 0) && (new_count < TWO_GIG_LIMIT))
-       bigio_count = new_count;
-
-    return orig_count;
-} /* end H5S_mpio_set_bigio_count() */
-
 
 /*-------------------------------------------------------------------------
  * Function:	H5S__mpio_all_type
@@ -160,6 +126,7 @@ H5S__mpio_all_type(const H5S_t *space, size_t elmt_size,
     hsize_t	total_bytes;
     hssize_t	snelmts;                /* Total number of elmts	(signed) */
     hsize_t	nelmts;                 /* Total number of elmts	*/
+    hsize_t     bigio_count;            /* Transition point to create derived type */
     herr_t	ret_value = SUCCEED;    /* Return value */
 
     FUNC_ENTER_STATIC
@@ -173,6 +140,7 @@ H5S__mpio_all_type(const H5S_t *space, size_t elmt_size,
     H5_CHECKED_ASSIGN(nelmts, hsize_t, snelmts, hssize_t);
 
     total_bytes = (hsize_t)elmt_size * nelmts;
+    bigio_count = H5_mpio_get_bigio_count();
 
     /* Verify that the size can be expressed as a 32 bit integer */
     if(bigio_count >= total_bytes) {
@@ -183,7 +151,7 @@ H5S__mpio_all_type(const H5S_t *space, size_t elmt_size,
     } /* end if */
     else {
         /* Create a LARGE derived datatype for this transfer */
-        if(H5S__mpio_create_large_type(total_bytes, 0, MPI_BYTE, new_type) < 0)
+        if(H5_mpio_create_large_type(total_bytes, 0, MPI_BYTE, new_type) < 0)
             HGOTO_ERROR(H5E_DATASPACE, H5E_BADTYPE, FAIL, "couldn't create a large datatype from the all selection")
         *count = 1;
         *is_derived_type = TRUE;
@@ -250,6 +218,7 @@ H5S__mpio_create_point_datatype(size_t elmt_size, hsize_t num_points,
     int            *blocks = NULL;      /* Array of block sizes for MPI hindexed create call */
     hsize_t        u;                   /* Local index variable */
 #endif
+    hsize_t        bigio_count;         /* Transition point to create derived type */
     int            mpi_code;            /* MPI error code */
     herr_t	   ret_value = SUCCEED; /* Return value */
 
@@ -260,6 +229,8 @@ H5S__mpio_create_point_datatype(size_t elmt_size, hsize_t num_points,
         HMPI_GOTO_ERROR(FAIL, "MPI_Type_contiguous failed", mpi_code)
     elmt_type_created = TRUE;
 
+    bigio_count = H5_mpio_get_bigio_count();
+
     /* Check whether standard or BIGIO processing will be employeed */
     if(bigio_count >= num_points) {
 #if MPI_VERSION >= 3
@@ -518,7 +489,7 @@ done:
  *              selection and so the memory datatype has to be permuted using the
  *              permutation map created by the file selection.
  *
- * Note:	This routine is called from H5S_mpio_space_type(), which is
+ * Note:	This routine is called from H5_mpio_space_type(), which is
  *              called first for the file dataspace and creates
  *
  * Return:	Non-negative on success, negative on failure.
@@ -678,6 +649,7 @@ H5S__mpio_reg_hyper_type(const H5S_t *space, size_t elmt_size,
         hsize_t count;
     } d[H5S_MAX_RANK];
 
+    hsize_t             bigio_count;            /* Transition point to create derived type */
     hsize_t		offset[H5S_MAX_RANK];
     hsize_t		max_xtent[H5S_MAX_RANK];
     H5S_hyper_dim_t	*diminfo;		/* [rank] */
@@ -696,6 +668,7 @@ H5S__mpio_reg_hyper_type(const H5S_t *space, size_t elmt_size,
     HDassert(space);
     HDassert(sizeof(MPI_Aint) >= sizeof(elmt_size));
 
+    bigio_count = H5_mpio_get_bigio_count();
     /* Initialize selection iterator */
     if(H5S_select_iter_init(&sel_iter, space, elmt_size, 0) < 0)
         HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, FAIL, "unable to initialize selection iterator")
@@ -824,7 +797,7 @@ if(H5DEBUG(S)) {
     } /* end if */
     else
         /* Create the compound datatype for this operation (> 2GB) */
-        if(H5S__mpio_create_large_type(elmt_size, 0, MPI_BYTE, &inner_type) < 0)
+        if(H5_mpio_create_large_type(elmt_size, 0, MPI_BYTE, &inner_type) < 0)
             HGOTO_ERROR(H5E_DATASPACE, H5E_BADTYPE, FAIL, "couldn't create a large inner datatype in hyper selection")
 
 /*******************************************************
@@ -878,7 +851,7 @@ if(H5DEBUG(S))
              * Again we need to check that the number of BLOCKS can fit into
              * a 32 bit integer */
             if(bigio_count < d[i].block) {
-                if(H5S__mpio_create_large_type(d[i].block, 0, inner_type, &block_type) < 0)
+                if(H5_mpio_create_large_type(d[i].block, 0, inner_type, &block_type) < 0)
                     HGOTO_ERROR(H5E_DATASPACE, H5E_BADTYPE, FAIL, "couldn't create a large block datatype in hyper selection")
             } /* end if */
             else
@@ -899,7 +872,7 @@ if(H5DEBUG(S))
              * we call the large type creation function to handle that
              */
             if(bigio_count < d[i].count) {
-                if(H5S__mpio_create_large_type(d[i].count, stride_in_bytes, block_type, &outer_type) < 0)
+                if(H5_mpio_create_large_type(d[i].count, stride_in_bytes, block_type, &outer_type) < 0)
                     HGOTO_ERROR(H5E_DATASPACE, H5E_BADTYPE, FAIL, "couldn't create a large outer datatype in hyper selection")
             } /* end if */
             /* otherwise a regular create_hvector will do */
@@ -1001,6 +974,7 @@ H5S__mpio_span_hyper_type(const H5S_t *space, size_t elmt_size,
     MPI_Datatype  elmt_type;            /* MPI datatype for an element */
     hbool_t elmt_type_is_derived = FALSE;       /* Whether the element type has been created */
     MPI_Datatype  span_type;            /* MPI datatype for overall span tree */
+    hsize_t       bigio_count;          /* Transition point to create derived type */
     hsize_t       down[H5S_MAX_RANK];   /* 'down' sizes for each dimension */
     uint64_t      op_gen;               /* Operation generation value */
     int           mpi_code;             /* MPI return code */
@@ -1014,13 +988,14 @@ H5S__mpio_span_hyper_type(const H5S_t *space, size_t elmt_size,
     HDassert(space->select.sel_info.hslab->span_lst);
     HDassert(space->select.sel_info.hslab->span_lst->head);
 
+    bigio_count = H5_mpio_get_bigio_count();
     /* Create the base type for an element */
     if(bigio_count >= elmt_size) {
         if(MPI_SUCCESS != (mpi_code = MPI_Type_contiguous((int)elmt_size, MPI_BYTE, &elmt_type)))
             HMPI_GOTO_ERROR(FAIL, "MPI_Type_contiguous failed", mpi_code)
     } /* end if */
     else
-        if(H5S__mpio_create_large_type(elmt_size, 0, MPI_BYTE, &elmt_type) < 0)
+        if(H5_mpio_create_large_type(elmt_size, 0, MPI_BYTE, &elmt_type) < 0)
             HGOTO_ERROR(H5E_DATASPACE, H5E_BADTYPE, FAIL, "couldn't create a large element datatype in span_hyper selection")
     elmt_type_is_derived = TRUE;
 
@@ -1124,8 +1099,10 @@ H5S__obtain_datatype(H5S_hyper_span_info_t *spans, const hsize_t *down,
     H5S_mpio_mpitype_list_t *type_list, uint64_t op_gen)
 {
     H5S_hyper_span_t      *span;                /* Hyperslab span to iterate with */
+    hsize_t               bigio_count;          /* Transition point to create derived type */
+
     size_t                alloc_count = 0;      /* Number of span tree nodes allocated at this level */
-    size_t                outercount;           /* Number of span tree nodes at this level */
+    size_t                outercount = 0;       /* Number of span tree nodes at this level */
     MPI_Datatype          *inner_type = NULL;
     hbool_t inner_types_freed = FALSE;          /* Whether the inner_type MPI datatypes have been freed */
     int                   *blocklen = NULL;
@@ -1140,6 +1117,7 @@ H5S__obtain_datatype(H5S_hyper_span_info_t *spans, const hsize_t *down,
     HDassert(spans);
     HDassert(type_list);
 
+    bigio_count = H5_mpio_get_bigio_count();
     /* Check if we've visited this span tree before */
     if(spans->op_gen != op_gen) {
         H5S_mpio_mpitype_node_t *type_node;     /* Pointer to new node in MPI data type list */
@@ -1185,7 +1163,7 @@ H5S__obtain_datatype(H5S_hyper_span_info_t *spans, const hsize_t *down,
                 H5_CHECK_OVERFLOW(nelmts, hsize_t, int)
                 blocklen[outercount]  = (int)nelmts;
 
-                if(bigio_count < blocklen[outercount])
+                if(bigio_count < (hsize_t)blocklen[outercount])
                     large_block = TRUE; /* at least one block type is large, so set this flag to true */
 
                 span = span->next;
@@ -1202,8 +1180,8 @@ H5S__obtain_datatype(H5S_hyper_span_info_t *spans, const hsize_t *down,
                     MPI_Datatype temp_type = MPI_DATATYPE_NULL;
 
                     /* create the block type from elmt_type while checking the 32 bit int limit */
-                    if(blocklen[u] > bigio_count) {
-                        if(H5S__mpio_create_large_type(blocklen[u], 0, *elmt_type, &temp_type) < 0)
+                    if((hsize_t)(blocklen[u]) > bigio_count) {
+                        if(H5_mpio_create_large_type(blocklen[u], 0, *elmt_type, &temp_type) < 0)
                             HGOTO_ERROR(H5E_DATASPACE, H5E_BADTYPE, FAIL, "couldn't create a large element datatype in span_hyper selection")
                     } /* end if */
                     else
@@ -1453,113 +1431,5 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5S_mpio_space_type() */
 
-
-/*-------------------------------------------------------------------------
- * Function:    H5S__mpio_create_large_type
- *
- * Purpose:     Create a large datatype of size larger than what a 32 bit integer
- *              can hold.
- *
- * Return:      Non-negative on success, negative on failure.
- *
- *              *new_type    the new datatype created
- *
- * Programmer:  Mohamad Chaarawi
- *
- *-------------------------------------------------------------------------
- */
-static herr_t
-H5S__mpio_create_large_type(hsize_t num_elements, MPI_Aint stride_bytes,
-    MPI_Datatype old_type, MPI_Datatype *new_type)
-{
-    int           num_big_types;          /* num times the 2G datatype will be repeated */
-    int           remaining_bytes;        /* the number of bytes left that can be held in an int value */
-    hsize_t       leftover;
-    int           block_len[2];
-    int           mpi_code;               /* MPI return code */
-    MPI_Datatype  inner_type, outer_type, leftover_type, type[2];
-    MPI_Aint      disp[2], old_extent;
-    herr_t        ret_value = SUCCEED;    /* Return value */
-
-    FUNC_ENTER_STATIC
-
-    /* Calculate how many Big MPI datatypes are needed to represent the buffer */
-    num_big_types = (int)(num_elements/bigio_count);
-    leftover = num_elements - num_big_types * (hsize_t)bigio_count;
-    H5_CHECKED_ASSIGN(remaining_bytes, int, leftover, hsize_t);
-
-    /* Create a contiguous datatype of size equal to the largest
-     * number that a 32 bit integer can hold x size of old type.
-     * If the displacement is 0, then the type is contiguous, otherwise
-     * use type_hvector to create the type with the displacement provided
-     */
-    if (0 == stride_bytes) {
-        if(MPI_SUCCESS != (mpi_code = MPI_Type_contiguous(bigio_count, old_type, &inner_type)))
-            HMPI_GOTO_ERROR(FAIL, "MPI_Type_contiguous failed", mpi_code)
-    } /* end if */
-    else
-        if(MPI_SUCCESS != (mpi_code = MPI_Type_create_hvector(bigio_count, 1, stride_bytes, old_type, &inner_type)))
-            HMPI_GOTO_ERROR(FAIL, "MPI_Type_create_hvector failed", mpi_code)
-
-    /* Create a contiguous datatype of the buffer (minus the remaining < 2GB part)
-     * If a stride is present, use hvector type
-     */
-    if(0 == stride_bytes) {
-        if(MPI_SUCCESS != (mpi_code = MPI_Type_contiguous(num_big_types, inner_type, &outer_type)))
-            HMPI_GOTO_ERROR(FAIL, "MPI_Type_contiguous failed", mpi_code)
-    } /* end if */
-    else
-        if(MPI_SUCCESS != (mpi_code = MPI_Type_create_hvector(num_big_types, 1, stride_bytes, inner_type, &outer_type)))
-            HMPI_GOTO_ERROR(FAIL, "MPI_Type_create_hvector failed", mpi_code)
-
-    MPI_Type_free(&inner_type);
-
-    /* If there is a remaining part create a contiguous/vector datatype and then
-     * use a struct datatype to encapsulate everything.
-     */
-    if(remaining_bytes) {
-        if(stride_bytes == 0) {
-            if(MPI_SUCCESS != (mpi_code = MPI_Type_contiguous(remaining_bytes, old_type, &leftover_type)))
-                HMPI_GOTO_ERROR(FAIL, "MPI_Type_contiguous failed", mpi_code)
-        } /* end if */
-        else
-            if(MPI_SUCCESS != (mpi_code = MPI_Type_create_hvector((int)(num_elements - (hsize_t)num_big_types * bigio_count), 1, stride_bytes, old_type, &leftover_type)))
-                HMPI_GOTO_ERROR(FAIL, "MPI_Type_create_hvector failed", mpi_code)
-
-        /* As of version 4.0, OpenMPI now turns off MPI-1 API calls by default,
-         * so we're using the MPI-2 version even though we don't need the lb
-         * value.
-         */
-        {
-            MPI_Aint unused_lb_arg;
-            MPI_Type_get_extent(old_type, &unused_lb_arg, &old_extent);
-        }
-
-        /* Set up the arguments for MPI_Type_struct constructor */
-        type[0] = outer_type;
-        type[1] = leftover_type;
-        block_len[0] = 1;
-        block_len[1] = 1;
-        disp[0] = 0;
-        disp[1] = (old_extent + stride_bytes) * num_big_types * (MPI_Aint)bigio_count;
-
-        if(MPI_SUCCESS != (mpi_code = MPI_Type_create_struct(2, block_len, disp, type, new_type)))
-            HMPI_GOTO_ERROR(FAIL, "MPI_Type_create_struct failed", mpi_code)
-
-        MPI_Type_free(&outer_type);
-        MPI_Type_free(&leftover_type);
-    } /* end if */
-    else
-        /* There are no remaining bytes so just set the new type to
-         * the outer type created */
-        *new_type = outer_type;
-
-    if(MPI_SUCCESS != (mpi_code = MPI_Type_commit(new_type)))
-        HMPI_GOTO_ERROR(FAIL, "MPI_Type_commit failed", mpi_code)
-
-done:
-    FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5S__mpio_create_large_type() */
-
 #endif  /* H5_HAVE_PARALLEL */
 
diff --git a/src/H5Sprivate.h b/src/H5Sprivate.h
index 0a9d2e7..3d68de0 100644
--- a/src/H5Sprivate.h
+++ b/src/H5Sprivate.h
@@ -307,7 +307,6 @@ H5_DLL herr_t H5S_select_iter_release(H5S_sel_iter_t *sel_iter);
 H5_DLL herr_t H5S_sel_iter_close(H5S_sel_iter_t *sel_iter);
 
 #ifdef H5_HAVE_PARALLEL
-H5_DLL hsize_t H5S_mpio_set_bigio_count(hsize_t new_count);
 H5_DLL herr_t H5S_mpio_space_type(const H5S_t *space, size_t elmt_size,
     /* out: */  MPI_Datatype *new_type,
                 int *count,
diff --git a/src/H5mpi.c b/src/H5mpi.c
index d48790b..f01e16a 100644
--- a/src/H5mpi.c
+++ b/src/H5mpi.c
@@ -22,6 +22,64 @@
 
 
 #ifdef H5_HAVE_PARALLEL
+
+/****************/
+/* Local Macros */
+/****************/
+#define TWO_GIG_LIMIT           (1 << 31)
+#ifndef H5_MAX_MPI_COUNT
+#define H5_MAX_MPI_COUNT        (1 << 30)
+#endif
+
+/*******************/
+/* Local Variables */
+/*******************/
+static hsize_t bigio_count = H5_MAX_MPI_COUNT;
+
+
+/*-------------------------------------------------------------------------
+ * Function:  H5_mpio_set_bigio_count
+ *
+ * Purpose:   Allow us to programatically change the switch point
+ *            when we utilize derived datatypes.  This is of
+ *            particular interest for allowing nightly testing
+ *
+ * Return:    The current/previous value of bigio_count.
+ *
+ * Programmer: Richard Warren,  March 10, 2017
+ *
+ *-------------------------------------------------------------------------
+ */
+hsize_t
+H5_mpio_set_bigio_count(hsize_t new_count)
+{
+    hsize_t orig_count = bigio_count;
+
+    if((new_count > 0) && (new_count < (hsize_t)TWO_GIG_LIMIT)) {
+       bigio_count = new_count;
+    }
+    return orig_count;
+} /* end H5_mpio_set_bigio_count() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:  H5_mpio_get_bigio_count
+ *
+ * Purpose:   Allow other HDF5 library functions to access
+ *            the current value for bigio_count.
+ *
+ * Return:    The current/previous value of bigio_count.
+ *
+ * Programmer: Richard Warren,  October 7, 2019
+ *
+ *-------------------------------------------------------------------------
+ */
+hsize_t
+H5_mpio_get_bigio_count()
+{
+    return bigio_count;
+}
+
 
 /*-------------------------------------------------------------------------
  * Function:    H5_mpi_comm_dup
@@ -392,5 +450,114 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5_mpi_info_cmp() */
 
+
+/*-------------------------------------------------------------------------
+ * Function:    H5_mpio_create_large_type
+ *
+ * Purpose:     Create a large datatype of size larger than what a 32 bit integer
+ *              can hold.
+ *
+ * Return:      Non-negative on success, negative on failure.
+ *
+ *              *new_type    the new datatype created
+ *
+ * Programmer:  Mohamad Chaarawi
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5_mpio_create_large_type(hsize_t num_elements, MPI_Aint stride_bytes,
+    MPI_Datatype old_type, MPI_Datatype *new_type)
+{
+    int           num_big_types;          /* num times the 2G datatype will be repeated */
+    int           remaining_bytes;        /* the number of bytes left that can be held in an int value */
+    hsize_t       leftover;
+    int           block_len[2];
+    int           mpi_code;               /* MPI return code */
+    MPI_Datatype  inner_type, outer_type, leftover_type, type[2];
+    MPI_Aint      disp[2], old_extent;
+    herr_t        ret_value = SUCCEED;    /* Return value */
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Calculate how many Big MPI datatypes are needed to represent the buffer */
+    num_big_types = (int)(num_elements/bigio_count);
+    leftover = num_elements - num_big_types * (hsize_t)bigio_count;
+    H5_CHECKED_ASSIGN(remaining_bytes, int, leftover, hsize_t);
+
+    /* Create a contiguous datatype of size equal to the largest
+     * number that a 32 bit integer can hold x size of old type.
+     * If the displacement is 0, then the type is contiguous, otherwise
+     * use type_hvector to create the type with the displacement provided
+     */
+    if (0 == stride_bytes) {
+        if(MPI_SUCCESS != (mpi_code = MPI_Type_contiguous(bigio_count, old_type, &inner_type)))
+            HMPI_GOTO_ERROR(FAIL, "MPI_Type_contiguous failed", mpi_code)
+    } /* end if */
+    else
+        if(MPI_SUCCESS != (mpi_code = MPI_Type_create_hvector(bigio_count, 1, stride_bytes, old_type, &inner_type)))
+            HMPI_GOTO_ERROR(FAIL, "MPI_Type_create_hvector failed", mpi_code)
+
+    /* Create a contiguous datatype of the buffer (minus the remaining < 2GB part)
+     * If a stride is present, use hvector type
+     */
+    if(0 == stride_bytes) {
+        if(MPI_SUCCESS != (mpi_code = MPI_Type_contiguous(num_big_types, inner_type, &outer_type)))
+            HMPI_GOTO_ERROR(FAIL, "MPI_Type_contiguous failed", mpi_code)
+    } /* end if */
+    else
+        if(MPI_SUCCESS != (mpi_code = MPI_Type_create_hvector(num_big_types, 1, stride_bytes, inner_type, &outer_type)))
+            HMPI_GOTO_ERROR(FAIL, "MPI_Type_create_hvector failed", mpi_code)
+
+    MPI_Type_free(&inner_type);
+
+    /* If there is a remaining part create a contiguous/vector datatype and then
+     * use a struct datatype to encapsulate everything.
+     */
+    if(remaining_bytes) {
+        if(stride_bytes == 0) {
+            if(MPI_SUCCESS != (mpi_code = MPI_Type_contiguous(remaining_bytes, old_type, &leftover_type)))
+                HMPI_GOTO_ERROR(FAIL, "MPI_Type_contiguous failed", mpi_code)
+        } /* end if */
+        else
+            if(MPI_SUCCESS != (mpi_code = MPI_Type_create_hvector((int)(num_elements - (hsize_t)num_big_types * bigio_count), 1, stride_bytes, old_type, &leftover_type)))
+                HMPI_GOTO_ERROR(FAIL, "MPI_Type_create_hvector failed", mpi_code)
+
+        /* As of version 4.0, OpenMPI now turns off MPI-1 API calls by default,
+         * so we're using the MPI-2 version even though we don't need the lb
+         * value.
+         */
+        {
+            MPI_Aint unused_lb_arg;
+            MPI_Type_get_extent(old_type, &unused_lb_arg, &old_extent);
+        }
+
+        /* Set up the arguments for MPI_Type_struct constructor */
+        type[0] = outer_type;
+        type[1] = leftover_type;
+        block_len[0] = 1;
+        block_len[1] = 1;
+        disp[0] = 0;
+        disp[1] = (old_extent + stride_bytes) * num_big_types * (MPI_Aint)bigio_count;
+
+        if(MPI_SUCCESS != (mpi_code = MPI_Type_create_struct(2, block_len, disp, type, new_type)))
+            HMPI_GOTO_ERROR(FAIL, "MPI_Type_create_struct failed", mpi_code)
+
+        MPI_Type_free(&outer_type);
+        MPI_Type_free(&leftover_type);
+    } /* end if */
+    else
+        /* There are no remaining bytes so just set the new type to
+         * the outer type created */
+        *new_type = outer_type;
+
+    if(MPI_SUCCESS != (mpi_code = MPI_Type_commit(new_type)))
+        HMPI_GOTO_ERROR(FAIL, "MPI_Type_commit failed", mpi_code)
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5_mpio_create_large_type() */
+
+
 #endif /* H5_HAVE_PARALLEL */
 
diff --git a/testpar/t_bigio.c b/testpar/t_bigio.c
index 9ca077c..fe96c83 100644
--- a/testpar/t_bigio.c
+++ b/testpar/t_bigio.c
@@ -4,7 +4,8 @@
 #include "H5Dprivate.h"                /* For Chunk tests */
 
 /* FILENAME and filenames must have the same number of names */
-const char *FILENAME[2]={ "bigio_test.h5",
+const char *FILENAME[3]={ "bigio_test.h5",
+                          "single_rank_independent_io.h5",
                            NULL
                         };
 
@@ -29,7 +30,8 @@ const char *FILENAME[2]={ "bigio_test.h5",
 #define DATASET5 "DSET5"
 #define DXFER_COLLECTIVE_IO 0x1  /* Collective IO*/
 #define DXFER_INDEPENDENT_IO 0x2 /* Independent IO collectively */
-#define DXFER_BIGCOUNT 536870916
+#define DXFER_BIGCOUNT (1 < 29)
+#define LARGE_DIM 1610612736
 
 #define HYPER 1
 #define POINT 2
@@ -40,7 +42,7 @@ typedef hsize_t B_DATATYPE;
 
 int facc_type = FACC_MPIO;        /*Test file access type */
 int dxfer_coll_type = DXFER_COLLECTIVE_IO;
-size_t bigcount = DXFER_BIGCOUNT;
+size_t bigcount = (size_t)DXFER_BIGCOUNT;
 int nerrors = 0;
 int mpi_size, mpi_rank;
 
@@ -51,6 +53,8 @@ static void coll_chunktest(const char* filename, int chunk_factor, int select_fa
                            int api_option, int file_selection, int mem_selection, int mode);
 hid_t create_faccess_plist(MPI_Comm comm, MPI_Info info, int l_facc_type);
 
+hsize_t H5_mpio_set_bigio_count(hsize_t new_count);
+
 /*
  * Setup the coordinates for point selection.
  */
@@ -478,22 +482,19 @@ static void
 dataset_big_write(void)
 {
 
-    hid_t xfer_plist;        /* Dataset transfer properties list */
-    hid_t sid;           /* Dataspace ID */
-    hid_t file_dataspace;    /* File dataspace ID */
-    hid_t mem_dataspace;    /* memory dataspace ID */
+    hid_t xfer_plist;                 /* Dataset transfer properties list */
+    hid_t sid;                        /* Dataspace ID */
+    hid_t file_dataspace;             /* File dataspace ID */
+    hid_t mem_dataspace;              /* memory dataspace ID */
     hid_t dataset;
-    hid_t datatype;        /* Datatype ID */
-    hsize_t dims[RANK];       /* dataset dim sizes */
-    hsize_t start[RANK];            /* for hyperslab setting */
-    hsize_t count[RANK], stride[RANK];        /* for hyperslab setting */
-    hsize_t block[RANK];            /* for hyperslab setting */
+    hsize_t dims[RANK];               /* dataset dim sizes */
+    hsize_t start[RANK];              /* for hyperslab setting */
+    hsize_t count[RANK],stride[RANK]; /* for hyperslab setting */
+    hsize_t block[RANK];              /* for hyperslab setting */
     hsize_t *coords = NULL;
-    int i;
-    herr_t ret;             /* Generic return value */
-    hid_t fid;                  /* HDF5 file ID */
-    hid_t acc_tpl;        /* File access templates */
-    hsize_t h;
+    herr_t ret;                       /* Generic return value */
+    hid_t fid;                        /* HDF5 file ID */
+    hid_t acc_tpl;                    /* File access templates */
     size_t num_points;
     B_DATATYPE * wdata;
 
@@ -806,8 +807,6 @@ dataset_big_read(void)
     hsize_t start[RANK];            /* for hyperslab setting */
     hsize_t count[RANK], stride[RANK];        /* for hyperslab setting */
     hsize_t block[RANK];            /* for hyperslab setting */
-    int i,j,k;
-    hsize_t h;
     size_t num_points;
     hsize_t *coords = NULL;
     herr_t ret;             /* Generic return value */
@@ -1120,6 +1119,63 @@ dataset_big_read(void)
 
 } /* dataset_large_readAll */
 
+static void
+single_rank_independent_io(void)
+{
+    if (mpi_rank == 0)
+        HDprintf("single_rank_independent_io\n");
+
+    if (MAINPROCESS) {
+        hsize_t dims[] = { LARGE_DIM };
+        hid_t file_id = -1;
+        hid_t fapl_id = -1;
+        hid_t dset_id = -1;
+        hid_t fspace_id = -1;
+        hid_t mspace_id = -1;
+        void *data = NULL;
+
+        fapl_id = H5Pcreate(H5P_FILE_ACCESS);
+	VRFY((fapl_id >= 0), "H5P_FILE_ACCESS");
+
+        H5Pset_fapl_mpio(fapl_id, MPI_COMM_SELF, MPI_INFO_NULL);
+        file_id = H5Fcreate(FILENAME[1], H5F_ACC_TRUNC, H5P_DEFAULT, fapl_id);
+        VRFY((file_id >= 0), "H5Dcreate2 succeeded");
+
+        fspace_id = H5Screate_simple(1, dims, NULL);
+        VRFY((fspace_id >= 0), "H5Screate_simple fspace_id succeeded");
+
+        /*
+         * Create and write to a >2GB dataset from a single rank.
+         */
+        dset_id = H5Dcreate2(file_id, "test_dset", H5T_NATIVE_INT, fspace_id,
+                  H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT);
+
+        VRFY((dset_id >= 0), "H5Dcreate2 succeeded");
+
+        data = malloc(LARGE_DIM * sizeof(int));
+
+        if (mpi_rank == 0)
+            H5Sselect_all(fspace_id);
+        else
+            H5Sselect_none(fspace_id);
+
+        dims[0] = LARGE_DIM;
+        mspace_id = H5Screate_simple(1, dims, NULL);
+        VRFY((mspace_id >= 0), "H5Screate_simple mspace_id succeeded");
+        H5Dwrite(dset_id, H5T_NATIVE_INT, mspace_id, fspace_id, H5P_DEFAULT, data);
+
+        free(data);
+        H5Sclose(mspace_id);
+        H5Sclose(fspace_id);
+        H5Pclose(fapl_id);
+        H5Dclose(dset_id);
+        H5Fclose(file_id);
+
+        HDremove(FILENAME[1]);
+
+    }
+    MPI_Barrier(MPI_COMM_WORLD);
+}
 
 /*
  * Create the appropriate File access property list
@@ -1395,7 +1451,6 @@ coll_chunktest(const char* filename,
 
   size_t  num_points;           /* for point selection */
   hsize_t *coords = NULL;       /* for point selection */
-  int i;
 
   /* Create the data space */
 
@@ -1873,7 +1928,7 @@ int main(int argc, char **argv)
     int ExpressMode = 0;
     hsize_t newsize = 1048576;
     /* Set the bigio processing limit to be 'newsize' bytes */
-    hsize_t oldsize = H5S_mpio_set_bigio_count(newsize);
+    hsize_t oldsize = H5_mpio_set_bigio_count(newsize);
 
     /* Having set the bigio handling to a size that is managable,
      * we'll set our 'bigcount' variable to be 2X that limit so
@@ -1918,6 +1973,8 @@ int main(int argc, char **argv)
       coll_chunk2();
       MPI_Barrier(MPI_COMM_WORLD);
       coll_chunk3();
+      MPI_Barrier(MPI_COMM_WORLD);
+      single_rank_independent_io();
     }
 
     /* turn off alarm */