[svn-r15397] Update to the h5perf files that includes bug fixes and extensions.

Tested on kagiso and abe.

1 files changed, 2188 insertions, 1970 deletions

diff --git a/perform/pio_engine.c b/perform/pio_engine.c
index f42a849..6f300c8 100644
--- a/perform/pio_engine.c
+++ b/perform/pio_engine.c
@@ -50,25 +50,25 @@
 #define ELMT_MPI_TYPE       MPI_BYTE
 #define ELMT_H5_TYPE        H5T_NATIVE_UCHAR
 
-#define GOTOERROR(errcode)	{ ret_code = errcode; goto done; }
-#define GOTODONE		{ goto done; }
+#define GOTOERROR(errcode)  { ret_code = errcode; goto done; }
+#define GOTODONE        { goto done; }
 #define ERRMSG(mesg) {                                                  \
     fprintf(stderr, "Proc %d: ", pio_mpi_rank_g);                       \
     fprintf(stderr, "*** Assertion failed (%s) at line %4d in %s\n",    \
-	    mesg, (int)__LINE__, __FILE__);                             \
+        mesg, (int)__LINE__, __FILE__);                             \
 }
 
 #define MSG(mesg) {                                     \
     fprintf(stderr, "Proc %d: ", pio_mpi_rank_g);       \
     fprintf(stderr, "(%s) at line %4d in %s\n",         \
-	    mesg, (int)__LINE__, __FILE__);             \
+        mesg, (int)__LINE__, __FILE__);             \
 }
 
 /* verify: if val is false (0), print mesg. */
 #define VRFY(val, mesg) do {                            \
     if (!val) {                                         \
-	ERRMSG(mesg);                                   \
-	GOTOERROR(FAIL);                                \
+    ERRMSG(mesg);                                   \
+    GOTOERROR(FAIL);                                \
     }                                                   \
 } while(0)
 
@@ -88,7 +88,7 @@ enum {
 };
 
 /* Global variables */
-static int	clean_file_g = -1;	/*whether to cleanup temporary test     */
+static int  clean_file_g = -1;  /*whether to cleanup temporary test     */
 /*files. -1 is not defined;             */
 /*0 is no cleanup; 1 is do cleanup      */
 
@@ -120,13 +120,13 @@ typedef union _file_descr {
 
 /* local functions */
 static char  *pio_create_filename(iotype iot, const char *base_name,
-	char *fullname, size_t size);
+    char *fullname, size_t size);
 static herr_t do_write(results *res, file_descr *fd, parameters *parms,
-	long ndsets, off_t nelmts, size_t buf_size, void *buffer);
+    long ndsets, off_t nelmts, size_t buf_size, void *buffer);
 static herr_t do_read(results *res, file_descr *fd, parameters *parms,
-	long ndsets, off_t nelmts, size_t buf_size, void *buffer /*out*/);
+    long ndsets, off_t nelmts, size_t buf_size, void *buffer /*out*/);
 static herr_t do_fopen(parameters *param, char *fname, file_descr *fd /*out*/,
-	int flags);
+    int flags);
 static herr_t do_fclose(iotype iot, file_descr *fd);
 static void do_cleanupfile(iotype iot, char *fname);
 
@@ -138,16 +138,16 @@ static void gpfs_clear_file_cache(int handle);
 static void gpfs_cancel_hints(int handle);
 static void gpfs_start_data_shipping(int handle, int num_insts);
 static void gpfs_start_data_ship_map(int handle, int partition_size,
-	int agent_count, int *agent_node_num);
+    int agent_count, int *agent_node_num);
 static void gpfs_stop_data_shipping(int handle);
 static void gpfs_invalidate_file_cache(const char *filename);
 #endif /* H5_HAVE_GPFS */
 
 /*
- * Function:		do_pio
- * Purpose:			PIO Engine where Parallel IO are executed.
- * Return:			results
- * Programmer:		Albert Cheng, Bill Wendling 2001/12/12
+ * Function:        do_pio
+ * Purpose:         PIO Engine where Parallel IO are executed.
+ * Return:          results
+ * Programmer:      Albert Cheng, Bill Wendling 2001/12/12
  * Modifications:
  *  Added 2D testing (Christian Chilan, 10. August 2005)
  */
@@ -158,28 +158,25 @@ do_pio(parameters param)
     herr_t      ret_code = 0;   /*return code                           */
     results     res;
 
-    file_descr	fd;
+    file_descr  fd;
     iotype      iot;
 
     char        fname[FILENAME_MAX];
-    long		nf;
+    long    nf;
     long        ndsets;
-    off_t       nbytes;                 /*number of bytes per dataset  */
-    off_t		snbytes;				/*general dataset size			*/
-    /*for 1D, it is the actual dataset size */
-    /*for 2D, it is the size of a side of the dataset square */
-
-    char        *buffer = NULL;         /*data buffer pointer           */
-
-    size_t      buf_size;               /*general buffer size in bytes     */
-    /*for 1D, it is the actual buffer size */
-    /*for 2D, it is the length of the buffer rectangle */
-
-    size_t      blk_size;               /*data block size in bytes      */
-    size_t		bsize;					/*actual buffer size			*/
+    off_t       nbytes;         /*number of bytes per dataset  */
+    off_t   snbytes;    /*general dataset size          */
+                                /*for 1D, it is the actual dataset size */
+                                /*for 2D, it is the size of a side of the dataset square */
+    char        *buffer = NULL; /*data buffer pointer           */
+    size_t      buf_size;       /*general buffer size in bytes     */
+                                /*for 1D, it is the actual buffer size */
+                                /*for 2D, it is the length of the buffer rectangle */
+    size_t      blk_size;       /*data block size in bytes      */
+    size_t  bsize;      /*actual buffer size            */
 
     /* HDF5 variables */
-    herr_t          hrc;                /*HDF5 return code              */
+    herr_t          hrc;        /*HDF5 return code              */
 
     /* Sanity check parameters */
 
@@ -187,22 +184,22 @@ do_pio(parameters param)
     iot = param.io_type;
 
     switch (iot) {
-	case MPIO:
-	    fd.mpifd = MPI_FILE_NULL;
-	    res.timers = pio_time_new(MPI_TIMER);
-	    break;
-	case POSIXIO:
-	    fd.posixfd = -1;
-	    res.timers = pio_time_new(MPI_TIMER);
-	    break;
-	case PHDF5:
-	    fd.h5fd = -1;
-	    res.timers = pio_time_new(MPI_TIMER);
-	    break;
-	default:
-	    /* unknown request */
-	    fprintf(stderr, "Unknown IO type request (%d)\n", iot);
-	    GOTOERROR(FAIL);
+    case MPIO:
+        fd.mpifd = MPI_FILE_NULL;
+        res.timers = pio_time_new(MPI_TIMER);
+        break;
+    case POSIXIO:
+        fd.posixfd = -1;
+        res.timers = pio_time_new(MPI_TIMER);
+        break;
+    case PHDF5:
+        fd.h5fd = -1;
+        res.timers = pio_time_new(MPI_TIMER);
+        break;
+    default:
+        /* unknown request */
+        fprintf(stderr, "Unknown IO type request (%d)\n", iot);
+        GOTOERROR(FAIL);
     }
 
     ndsets = param.num_dsets;       /* number of datasets per file          */
@@ -210,152 +207,164 @@ do_pio(parameters param)
     buf_size = param.buf_size;
     blk_size = param.blk_size;
 
-    if (param.dim2d==0){
-	snbytes = nbytes;				/* General dataset size		*/
-	bsize = buf_size;				/* Actual buffer size		*/
+    if (!param.dim2d){
+        snbytes = nbytes;   /* General dataset size     */
+        bsize = buf_size;   /* Actual buffer size       */
     }
     else {
-	snbytes = (off_t)sqrt(nbytes);	/* General dataset size		*/
-	bsize = buf_size * blk_size;	/* Actual buffer size		*/
+        snbytes = (off_t)sqrt(nbytes);  /* General dataset size     */
+        bsize = buf_size * blk_size;    /* Actual buffer size       */
     }
 
     if (param.num_files < 0 ) {
-	fprintf(stderr,
-		"number of files must be >= 0 (%ld)\n",
-		param.num_files);
-	GOTOERROR(FAIL);
+    fprintf(stderr,
+        "number of files must be >= 0 (%ld)\n",
+        param.num_files);
+    GOTOERROR(FAIL);
     }
 
     if (ndsets < 0 ) {
-	fprintf(stderr,
-		"number of datasets per file must be >= 0 (%ld)\n",
-		ndsets);
-	GOTOERROR(FAIL);
+    fprintf(stderr,
+        "number of datasets per file must be >= 0 (%ld)\n",
+        ndsets);
+    GOTOERROR(FAIL);
     }
 
     if (param.num_procs <= 0 ) {
-	fprintf(stderr,
-		"maximum number of process to use must be > 0 (%d)\n",
-		param.num_procs);
-	GOTOERROR(FAIL);
+    fprintf(stderr,
+        "maximum number of process to use must be > 0 (%d)\n",
+        param.num_procs);
+    GOTOERROR(FAIL);
     }
 
     /* Validate transfer buffer size & block size*/
     if(blk_size<=0) {
-	HDfprintf(stderr,
-		"Transfer block size (%Hd) must be > 0\n", (long_long)blk_size);
-	GOTOERROR(FAIL);
+    HDfprintf(stderr,
+        "Transfer block size (%Hd) must be > 0\n", (long_long)blk_size);
+    GOTOERROR(FAIL);
     }
     if(buf_size<=0) {
-	HDfprintf(stderr,
-		"Transfer buffer size (%Hd) must be > 0\n", (long_long)buf_size);
-	GOTOERROR(FAIL);
+    HDfprintf(stderr,
+        "Transfer buffer size (%Hd) must be > 0\n", (long_long)buf_size);
+    GOTOERROR(FAIL);
     }
     if ((buf_size % blk_size) != 0){
-	HDfprintf(stderr,
-		"Transfer buffer size (%Hd) must be a multiple of the "
-		"interleaved I/O block size (%Hd)\n",
-		(long_long)buf_size, (long_long)blk_size);
-	GOTOERROR(FAIL);
+    HDfprintf(stderr,
+        "Transfer buffer size (%Hd) must be a multiple of the "
+        "interleaved I/O block size (%Hd)\n",
+        (long_long)buf_size, (long_long)blk_size);
+    GOTOERROR(FAIL);
     }
     if((snbytes%pio_mpi_nprocs_g)!=0) {
-	HDfprintf(stderr,
-		"Dataset size (%Hd) must be a multiple of the "
-		"number of processes (%d)\n",
-		(long_long)nbytes, pio_mpi_nprocs_g);
-	GOTOERROR(FAIL);
+    HDfprintf(stderr,
+        "Dataset size (%Hd) must be a multiple of the "
+        "number of processes (%d)\n",
+        (long_long)snbytes, pio_mpi_nprocs_g);
+    GOTOERROR(FAIL);
     }
-    if(((snbytes/pio_mpi_nprocs_g)%buf_size)!=0) {
-	HDfprintf(stderr,
-		"Dataset size/process (%Hd) must be a multiple of the "
-		"trasfer buffer size (%Hd)\n",
-		(long_long)(nbytes/pio_mpi_nprocs_g), (long_long)buf_size);
-	GOTOERROR(FAIL);
+
+    if (!param.dim2d){
+        if(((snbytes/pio_mpi_nprocs_g)%buf_size)!=0) {
+        HDfprintf(stderr,
+            "Dataset size/process (%Hd) must be a multiple of the "
+            "trasfer buffer size (%Hd)\n",
+            (long_long)(snbytes/pio_mpi_nprocs_g), (long_long)buf_size);
+        GOTOERROR(FAIL);
+        }
+    }
+    else {
+        if((snbytes%buf_size)!=0) {
+        HDfprintf(stderr,
+            "Dataset side size (%Hd) must be a multiple of the "
+            "trasfer buffer size (%Hd)\n",
+            (long_long)snbytes, (long_long)buf_size);
+        GOTOERROR(FAIL);
+        }
     }
 
     /* Allocate transfer buffer */
     if ((buffer = malloc(bsize)) == NULL){
-	HDfprintf(stderr, "malloc for transfer buffer size (%Hd) failed\n",
-		(long_long)(bsize));
-	GOTOERROR(FAIL);
+    HDfprintf(stderr, "malloc for transfer buffer size (%Hd) failed\n",
+        (long_long)(bsize));
+    GOTOERROR(FAIL);
     }
 
     if (pio_debug_level >= 4) {
-	int myrank;
+    int myrank;
 
-	MPI_Comm_rank(pio_comm_g, &myrank);
+    MPI_Comm_rank(pio_comm_g, &myrank);
 
-	/* output all of the times for all iterations */
-	if (myrank == 0)
-	    fprintf(output, "Timer details:\n");
+    /* output all of the times for all iterations */
+    if (myrank == 0)
+        fprintf(output, "Timer details:\n");
     }
 
     for (nf = 1; nf <= param.num_files; nf++) {
-	/*
-	 * Write performance measurement
-	 */
-	/* Open file for write */
-	char base_name[256];
-
-	sprintf(base_name, "#pio_tmp_%lu", nf);
-	pio_create_filename(iot, base_name, fname, sizeof(fname));
-	if (pio_debug_level > 0)
-	    HDfprintf(output, "rank %d: data filename=%s\n",
-		    pio_mpi_rank_g, fname);
-
-	/* Need barrier to make sure everyone starts at the same time */
-	MPI_Barrier(pio_comm_g);
-
-	set_time(res.timers, HDF5_GROSS_WRITE_FIXED_DIMS, START);
-	hrc = do_fopen(&param, fname, &fd, PIO_CREATE | PIO_WRITE);
-
-	VRFY((hrc == SUCCESS), "do_fopen failed");
-
-	set_time(res.timers, HDF5_FINE_WRITE_FIXED_DIMS, START);
-	hrc = do_write(&res, &fd, &param, ndsets, nbytes, buf_size, buffer);
-	hrc == SUCCESS;
-	set_time(res.timers, HDF5_FINE_WRITE_FIXED_DIMS, STOP);
-
-	VRFY((hrc == SUCCESS), "do_write failed");
-
-	/* Close file for write */
-	hrc = do_fclose(iot, &fd);
-
-	set_time(res.timers, HDF5_GROSS_WRITE_FIXED_DIMS, STOP);
-	VRFY((hrc == SUCCESS), "do_fclose failed");
-
-	if (!param.h5_write_only) {
-	    /*
-	     * Read performance measurement
-	     */
-	    /* Need barrier to make sure everyone is done writing and has
-	     * closed the file.  Also to make sure everyone starts reading
-	     * at the same time.
-	     */
-	    MPI_Barrier(pio_comm_g);
-
-	    /* Open file for read */
-	    set_time(res.timers, HDF5_GROSS_READ_FIXED_DIMS, START);
-	    hrc = do_fopen(&param, fname, &fd, PIO_READ);
-
-	    VRFY((hrc == SUCCESS), "do_fopen failed");
-
-	    set_time(res.timers, HDF5_FINE_READ_FIXED_DIMS, START);
-	    hrc = do_read(&res, &fd, &param, ndsets, nbytes, buf_size, buffer);
-	    set_time(res.timers, HDF5_FINE_READ_FIXED_DIMS, STOP);
-	    VRFY((hrc == SUCCESS), "do_read failed");
-
-	    /* Close file for read */
-	    hrc = do_fclose(iot, &fd);
-
-	    set_time(res.timers, HDF5_GROSS_READ_FIXED_DIMS, STOP);
-	    VRFY((hrc == SUCCESS), "do_fclose failed");
-	}
-
-	/* Need barrier to make sure everyone is done with the file */
-	/* before it may be removed by do_cleanupfile */
-	MPI_Barrier(pio_comm_g);
-	do_cleanupfile(iot, fname);
+    /*
+     * Write performance measurement
+     */
+    /* Open file for write */
+    char base_name[256];
+
+    sprintf(base_name, "#pio_tmp_%lu", nf);
+    pio_create_filename(iot, base_name, fname, sizeof(fname));
+    if (pio_debug_level > 0)
+        HDfprintf(output, "rank %d: data filename=%s\n",
+            pio_mpi_rank_g, fname);
+
+    /* Need barrier to make sure everyone starts at the same time */
+    MPI_Barrier(pio_comm_g);
+
+    set_time(res.timers, HDF5_GROSS_WRITE_FIXED_DIMS, START);
+    hrc = do_fopen(&param, fname, &fd, PIO_CREATE | PIO_WRITE);
+
+    VRFY((hrc == SUCCESS), "do_fopen failed");
+
+    set_time(res.timers, HDF5_FINE_WRITE_FIXED_DIMS, START);
+    hrc = do_write(&res, &fd, &param, ndsets, nbytes, buf_size, buffer);
+    hrc == SUCCESS;
+    set_time(res.timers, HDF5_FINE_WRITE_FIXED_DIMS, STOP);
+
+    VRFY((hrc == SUCCESS), "do_write failed");
+
+    /* Close file for write */
+    hrc = do_fclose(iot, &fd);
+
+    set_time(res.timers, HDF5_GROSS_WRITE_FIXED_DIMS, STOP);
+    VRFY((hrc == SUCCESS), "do_fclose failed");
+
+    if (!param.h5_write_only) {
+        /*
+         * Read performance measurement
+         */
+        /* Need barrier to make sure everyone is done writing and has
+         * closed the file.  Also to make sure everyone starts reading
+         * at the same time.
+         */
+        MPI_Barrier(pio_comm_g);
+
+        /* Open file for read */
+        set_time(res.timers, HDF5_GROSS_READ_FIXED_DIMS, START);
+        hrc = do_fopen(&param, fname, &fd, PIO_READ);
+
+        VRFY((hrc == SUCCESS), "do_fopen failed");
+
+        set_time(res.timers, HDF5_FINE_READ_FIXED_DIMS, START);
+        hrc = do_read(&res, &fd, &param, ndsets, nbytes, buf_size, buffer);
+        set_time(res.timers, HDF5_FINE_READ_FIXED_DIMS, STOP);
+        VRFY((hrc == SUCCESS), "do_read failed");
+
+        /* Close file for read */
+        hrc = do_fclose(iot, &fd);
+
+        set_time(res.timers, HDF5_GROSS_READ_FIXED_DIMS, STOP);
+        VRFY((hrc == SUCCESS), "do_fclose failed");
+    }
+
+    /* Need barrier to make sure everyone is done with the file */
+    /* before it may be removed by do_cleanupfile */
+    MPI_Barrier(pio_comm_g);
+    do_cleanupfile(iot, fname);
     }
 
 done:
@@ -365,23 +374,23 @@ done:
     /* close any opened files */
     /* no remove(fname) because that should have happened normally. */
     switch (iot) {
-	case POSIXIO:
-	    if (fd.posixfd != -1)
-		hrc = do_fclose(iot, &fd);
-	    break;
-	case MPIO:
-	    if (fd.mpifd != MPI_FILE_NULL)
-		hrc = do_fclose(iot, &fd);
-	    break;
-	case PHDF5:
-	    if (fd.h5fd != -1)
-		hrc = do_fclose(iot, &fd);
-	    break;
+    case POSIXIO:
+        if (fd.posixfd != -1)
+        hrc = do_fclose(iot, &fd);
+        break;
+    case MPIO:
+        if (fd.mpifd != MPI_FILE_NULL)
+        hrc = do_fclose(iot, &fd);
+        break;
+    case PHDF5:
+        if (fd.h5fd != -1)
+        hrc = do_fclose(iot, &fd);
+        break;
     }
 
     /* release generic resources */
     if(buffer)
-	free(buffer);
+    free(buffer);
     res.ret_code = ret_code;
     return res;
 }
@@ -404,20 +413,20 @@ pio_create_filename(iotype iot, const char *base_name, char *fullname, size_t si
     size_t i, j;
 
     if (!base_name || !fullname || size < 1)
-	return NULL;
+    return NULL;
 
     memset(fullname, 0, size);
 
     switch (iot) {
-	case POSIXIO:
-	    suffix = ".posix";
-	    break;
-	case MPIO:
-	    suffix = ".mpio";
-	    break;
-	case PHDF5:
-	    suffix = ".h5";
-	    break;
+    case POSIXIO:
+        suffix = ".posix";
+        break;
+    case MPIO:
+        suffix = ".mpio";
+        break;
+    case PHDF5:
+        suffix = ".h5";
+        break;
     }
 
     /* First use the environment variable and then try the constant */
@@ -425,118 +434,125 @@ pio_create_filename(iotype iot, const char *base_name, char *fullname, size_t si
 
 #ifdef HDF5_PARAPREFIX
     if (!prefix)
-	prefix = HDF5_PARAPREFIX;
+    prefix = HDF5_PARAPREFIX;
 #endif  /* HDF5_PARAPREFIX */
 
     /* Prepend the prefix value to the base name */
     if (prefix && *prefix) {
-	/* If the prefix specifies the HDF5_PARAPREFIX directory, then
-	 * default to using the "/tmp/$USER" or "/tmp/$LOGIN"
-	 * directory instead. */
-	register char *user, *login, *subdir;
-
-	user = getenv("USER");
-	login = getenv("LOGIN");
-	subdir = (user ? user : login);
-
-	if (subdir) {
-	    for (i = 0; i < size && prefix[i]; i++)
-		fullname[i] = prefix[i];
-
-	    fullname[i++] = '/';
-
-	    for (j = 0; i < size && subdir[j]; i++, j++)
-		fullname[i] = subdir[j];
-	} else {
-	    /* We didn't append the prefix yet */
-	    strncpy(fullname, prefix, MIN(strlen(prefix), size));
-	}
-
-	if ((strlen(fullname) + strlen(base_name) + 1) < size) {
-	    /* Append the base_name with a slash first. Multiple slashes are
-	     * handled below. */
-	    h5_stat_t buf;
-
-	    if (HDstat(fullname, &buf) < 0)
-		/* The directory doesn't exist just yet */
-		if (mkdir(fullname, (mode_t)0755) < 0 && errno != EEXIST) {
-		    /* We couldn't make the "/tmp/${USER,LOGIN}" subdirectory.
-		     * Default to PREFIX's original prefix value. */
-		    strcpy(fullname, prefix);
-		}
-
-	    strcat(fullname, "/");
-	    strcat(fullname, base_name);
-	} else {
-	    /* Buffer is too small */
-	    return NULL;
-	}
+    /* If the prefix specifies the HDF5_PARAPREFIX directory, then
+     * default to using the "/tmp/$USER" or "/tmp/$LOGIN"
+     * directory instead. */
+    register char *user, *login, *subdir;
+
+    user = getenv("USER");
+    login = getenv("LOGIN");
+    subdir = (user ? user : login);
+
+    if (subdir) {
+        for (i = 0; i < size && prefix[i]; i++)
+        fullname[i] = prefix[i];
+
+        fullname[i++] = '/';
+
+        for (j = 0; i < size && subdir[j]; i++, j++)
+        fullname[i] = subdir[j];
+    } else {
+        /* We didn't append the prefix yet */
+        strncpy(fullname, prefix, MIN(strlen(prefix), size));
+    }
+
+    if ((strlen(fullname) + strlen(base_name) + 1) < size) {
+        /* Append the base_name with a slash first. Multiple slashes are
+         * handled below. */
+        h5_stat_t buf;
+
+        if (HDstat(fullname, &buf) < 0)
+        /* The directory doesn't exist just yet */
+        if (mkdir(fullname, (mode_t)0755) < 0 && errno != EEXIST) {
+            /* We couldn't make the "/tmp/${USER,LOGIN}" subdirectory.
+             * Default to PREFIX's original prefix value. */
+            strcpy(fullname, prefix);
+        }
+
+        strcat(fullname, "/");
+        strcat(fullname, base_name);
+    } else {
+        /* Buffer is too small */
+        return NULL;
+    }
     } else if (strlen(base_name) >= size) {
-	/* Buffer is too small */
-	return NULL;
+    /* Buffer is too small */
+    return NULL;
     } else {
-	strcpy(fullname, base_name);
+    strcpy(fullname, base_name);
     }
 
     /* Append a suffix */
     if (suffix) {
-	if (strlen(fullname) + strlen(suffix) >= size)
-	    return NULL;
+    if (strlen(fullname) + strlen(suffix) >= size)
+        return NULL;
 
-	strcat(fullname, suffix);
+    strcat(fullname, suffix);
     }
 
     /* Remove any double slashes in the filename */
     for (ptr = fullname, i = j = 0; ptr && i < size; i++, ptr++) {
-	if (*ptr != '/' || last != '/')
-	    fullname[j++] = *ptr;
+    if (*ptr != '/' || last != '/')
+        fullname[j++] = *ptr;
 
-	last = *ptr;
+    last = *ptr;
     }
 
     return fullname;
 }
 
 /*
- * Function:		do_write
- * Purpose:			Write the required amount of data to the file.
- * Return:			SUCCESS or FAIL
- * Programmer:		Albert Cheng, Bill Wendling, 2001/12/13
+ * Function:        do_write
+ * Purpose:         Write the required amount of data to the file.
+ * Return:          SUCCESS or FAIL
+ * Programmer:      Albert Cheng, Bill Wendling, 2001/12/13
  * Modifications:
  *  Added 2D testing (Christian Chilan, 10. August 2005)
  */
     static herr_t
 do_write(results *res, file_descr *fd, parameters *parms, long ndsets,
-	off_t nbytes, size_t buf_size, void *buffer)
+    off_t nbytes, size_t buf_size, void *buffer)
 {
     int         ret_code = SUCCESS;
     int         rc;             /*routine return code                   */
     long        ndset;
     size_t      blk_size;       /* The block size to subdivide the xfer buffer into */
     off_t       nbytes_xfer;    /* Total number of bytes transferred so far */
+    size_t      nbytes_xfer_advance; /* Number of bytes transferred in a single I/O operation */
     size_t      nbytes_toxfer;  /* Number of bytes to transfer a particular time */
     char        dname[64];
     off_t       dset_offset=0;  /*dataset offset in a file              */
     off_t       bytes_begin[2];    /*first elmt this process transfer      */
     off_t       bytes_count;    /*number of elmts this process transfer */
-    off_t		snbytes=0;		/*size of a side of the dataset square  */
+    off_t       snbytes=0;  /*size of a side of the dataset square  */
     unsigned char *buf_p;       /* Current buffer pointer               */
 
     /* POSIX variables */
     off_t       file_offset;    /* File offset of the next transfer     */
+    off_t       file_offset_advance;    /* File offset advance after each I/O operation */
     off_t       posix_file_offset;    /* Base file offset of the next transfer      */
 
     /* MPI variables */
-    MPI_Offset  mpi_file_offset;/* Base file offset of the next transfer*/
-    MPI_Offset	mpi_offset;     /* Offset in MPI file                   */
-    MPI_Datatype mpi_file_type; /* MPI derived type for 1D file            */
-    MPI_Datatype mpi_blk_type;  /* MPI derived type for 1D buffer          */
-    MPI_Datatype mpi_cont_type; /* MPI derived type for 2D contiguous file */
-    MPI_Datatype contig_cont;	/* MPI derived type for 2D contiguous buffer */
-    MPI_Datatype mpi_inter_type;/* MPI derived type for 2D interleaved file  */
-    MPI_Datatype contig_inter;  /* MPI derived type for 2D interleaved buffer*/
-    MPI_Status	mpi_status;
-    int         mrc;            /* MPI return code                      */
+    MPI_Offset  mpi_file_offset;    /* Base file offset of the next transfer*/
+    MPI_Offset  mpi_offset;         /* Offset in MPI file                   */
+    MPI_Offset  mpi_offset_advance; /* Offset advance after each I/O operation */
+    MPI_Datatype mpi_file_type;     /* MPI derived type for 1D file            */
+    MPI_Datatype mpi_blk_type;      /* MPI derived type for 1D buffer          */
+    MPI_Datatype mpi_cont_type;     /* MPI derived type for 2D contiguous file */
+    MPI_Datatype mpi_partial_buffer_cont;       /* MPI derived type for partial 2D contiguous buffer */
+    MPI_Datatype mpi_inter_type;    /* MPI derived type for 2D interleaved file  */
+    MPI_Datatype mpi_partial_buffer_inter;      /* MPI derived type for partial 2D interleaved buffer */
+    MPI_Datatype mpi_full_buffer;       /* MPI derived type for 2D full buffer */
+    MPI_Datatype mpi_full_chunk;        /* MPI derived type for 2D full chunk */
+    MPI_Datatype mpi_chunk_inter_type;  /* MPI derived type for 2D chunk interleaved file */
+    MPI_Datatype mpi_collective_type;   /* Generic MPI derived type for 2D collective access */
+    MPI_Status  mpi_status;
+    int         mrc;                /* MPI return code                      */
 
     /* HDF5 variables */
     herr_t      hrc;                    /*HDF5 return code              */
@@ -544,11 +560,11 @@ do_write(results *res, file_descr *fd, parameters *parms, long ndsets,
     hid_t       h5dset_space_id = -1;   /*dataset space ID              */
     hid_t       h5mem_space_id = -1;    /*memory dataspace ID           */
     hid_t       h5ds_id = -1;           /*dataset handle                */
-    hsize_t	h5block[2];		/*dataspace selection           */
-    hsize_t	h5stride[2];
-    hsize_t	h5count[2];
-    hsize_t	h5start[2];
-    hssize_t	h5offset[2];            /* Selection offset within dataspace */
+    hsize_t     h5block[2];     /*dataspace selection           */
+    hsize_t     h5stride[2];
+    hsize_t     h5count[2];
+    hsize_t     h5start[2];
+    hssize_t    h5offset[2];            /* Selection offset within dataspace */
     hid_t       h5dcpl = -1;            /* Dataset creation property list */
     hid_t       h5dxpl = -1;            /* Dataset transfer property list */
 
@@ -566,41 +582,47 @@ do_write(results *res, file_descr *fd, parameters *parms, long ndsets,
      */
 
     /* 1D dataspace */
-    if (parms->dim2d==0){
-	if (parms->interleaved==0) {
-	    /* Contiguous Pattern: */
-	    bytes_begin[0] = (off_t)(((double)nbytes*pio_mpi_rank_g)/pio_mpi_nprocs_g);
-	} /* end if */
-	else {
-	    /* Interleaved Pattern: */
-	    bytes_begin[0] = (off_t)(blk_size*pio_mpi_rank_g);
-	} /* end else */
-	/* Prepare buffer for verifying data */
-	if (parms->verify)
-	    memset(buffer,pio_mpi_rank_g+1,buf_size);
+    if (!parms->dim2d){
+        /* Contiguous Pattern: */
+        if (!parms->interleaved) {
+            bytes_begin[0] = (off_t)(((double)nbytes*pio_mpi_rank_g)/pio_mpi_nprocs_g);
+        } /* end if */
+        /* Interleaved Pattern: */
+        else {
+            bytes_begin[0] = (off_t)(blk_size*pio_mpi_rank_g);
+        } /* end else */
+
+        /* Prepare buffer for verifying data */
+        if (parms->verify)
+            memset(buffer,pio_mpi_rank_g+1,buf_size);
     }/* end if */
     /* 2D dataspace */
     else {
-	snbytes = (off_t)sqrt(nbytes);
-	/* nbytes is always the number of bytes per dataset (1D or 2D). If the
-	   dataspace is 2D, snbytes is the size of a side of the dataset square.
-	 */
-	if (parms->interleaved==0) {
-	    /* Contiguous Pattern: */
-	    bytes_begin[0] = (off_t)((double)snbytes*pio_mpi_rank_g / pio_mpi_nprocs_g);
-	    bytes_begin[1] = 0;
-	} /* end if */
-	else {
-	    /* Interleaved Pattern: */
-	    bytes_begin[0] = 0;
-	    bytes_begin[1] = (off_t)(blk_size*pio_mpi_rank_g);
-	} /* end else */
-	/* Prepare buffer for verifying data */
-	if (parms->verify)
-	    memset(buffer,pio_mpi_rank_g+1,buf_size*blk_size);
-    }
+        /* nbytes is always the number of bytes per dataset (1D or 2D). If the
+           dataspace is 2D, snbytes is the size of a side of the dataset square.
+         */
+        snbytes = (off_t)sqrt(nbytes);
+
+        /* Contiguous Pattern: */
+        if (!parms->interleaved) {
+            bytes_begin[0] = (off_t)((double)snbytes*pio_mpi_rank_g / pio_mpi_nprocs_g);
+            bytes_begin[1] = 0;
+        } /* end if */
+        /* Interleaved Pattern: */
+        else {
+            bytes_begin[0] = 0;
+
+            if(!parms->h5_use_chunks || parms->io_type==PHDF5) 
+                bytes_begin[1] = (off_t)(blk_size*pio_mpi_rank_g);
+            else
+                bytes_begin[1] = (off_t)(blk_size*blk_size*pio_mpi_rank_g);
+        } /* end else */
+
+        /* Prepare buffer for verifying data */
+        if (parms->verify)
+            memset(buffer,pio_mpi_rank_g+1,buf_size*blk_size);
+    } /* end else */
 
-    /* end else */
 
     /* Calculate the total number of bytes (bytes_count) to be
      * transferred by this process. It may be different for different
@@ -613,798 +635,897 @@ do_write(results *res, file_descr *fd, parameters *parms, long ndsets,
      * (This is tricky, don't mess with the formula, rounding errors
      * can easily get introduced) */
     bytes_count = (off_t)(((double)nbytes*(pio_mpi_rank_g+1)) / pio_mpi_nprocs_g)
-	- (off_t)(((double)nbytes*pio_mpi_rank_g) / pio_mpi_nprocs_g);
+    - (off_t)(((double)nbytes*pio_mpi_rank_g) / pio_mpi_nprocs_g);
 
     /* debug */
     if (pio_debug_level >= 4) {
-	HDprint_rank(output);
-	HDfprintf(output, "Debug(do_write): "
-		"buf_size=%Hd, bytes_begin=%Hd, bytes_count=%Hd\n",
-		(long_long)buf_size, (long_long)bytes_begin,
-		(long_long)bytes_count);
+    HDprint_rank(output);
+    HDfprintf(output, "Debug(do_write): "
+        "buf_size=%Hd, bytes_begin=%Hd, bytes_count=%Hd\n",
+        (long_long)buf_size, (long_long)bytes_begin,
+        (long_long)bytes_count);
     }
 
     /* I/O Access specific setup */
     switch (parms->io_type) {
-	case POSIXIO:
-	    /* No extra setup */
-	    break;
-
-	case MPIO: /* MPI-I/O setup */
-	    /* 1D dataspace */
-	    if (parms->dim2d==0){
-		/* Build block's derived type */
-		mrc = MPI_Type_contiguous((int)blk_size,
-			MPI_BYTE, &mpi_blk_type);
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
-
-		/* Build file's derived type */
-		mrc = MPI_Type_vector((int)(buf_size/blk_size), (int)1,
-			(int)pio_mpi_nprocs_g, mpi_blk_type, &mpi_file_type);
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
-
-		/* Commit file type */
-		mrc = MPI_Type_commit( &mpi_file_type );
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
-
-		/* Commit buffer type */
-		mrc = MPI_Type_commit( &mpi_blk_type );
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
-	    } /* end if */
-	    /* 2D dataspace */
-	    else {
-		/* Build partial buffer derived type for contiguous access */
-		mrc = MPI_Type_contiguous((int)buf_size, MPI_BYTE,
-			&contig_cont);
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
-
-		/* Build contiguous file's derived type */
-		mrc = MPI_Type_vector((int)blk_size, (int)1, (int)(snbytes/buf_size),
-			contig_cont, &mpi_cont_type);
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
-
-		/* Commit contiguous file type */
-		mrc = MPI_Type_commit(&mpi_cont_type);
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
-
-		/* Build partial buffer derived type for interleaved access */
-		mrc = MPI_Type_contiguous((int)blk_size, MPI_BYTE,
-			&contig_inter);
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
-
-		/* Build interleaved file's derived type */
-		mrc = MPI_Type_vector((int)buf_size, (int)1, (int)(snbytes/blk_size),
-			contig_inter, &mpi_inter_type);
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
-
-		/* Commit interleaved file type */
-		mrc = MPI_Type_commit(&mpi_inter_type);
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
-	    } /* end else */
-	    break;
-
-	case PHDF5: /* HDF5 setup */
-	    /* 1D dataspace */
-	    if (parms->dim2d==0){
-		if(nbytes>0) {
-		    /* define a contiguous dataset of nbytes native bytes */
-		    h5dims[0] = nbytes;
-		    h5dset_space_id = H5Screate_simple(1, h5dims, NULL);
-		    VRFY((h5dset_space_id >= 0), "H5Screate_simple");
-
-		    /* Set up the file dset space id to select the pattern to access */
-		    if (parms->interleaved==0){
-			/* Contiguous pattern */
-			h5start[0] = bytes_begin[0];
-			h5stride[0] = h5block[0] = blk_size;
-			h5count[0] = buf_size/blk_size;
-		    } /* end if */
-		    else {
-			/* Interleaved access pattern */
-			/* Skip offset over blocks of other processes */
-			h5start[0] = bytes_begin[0];
-			h5stride[0] = blk_size*pio_mpi_nprocs_g;
-			h5block[0] = blk_size;
-			h5count[0] = buf_size/blk_size;
-		    } /* end else */
-		    hrc = H5Sselect_hyperslab(h5dset_space_id, H5S_SELECT_SET,
-			    h5start, h5stride, h5count, h5block);
-		    VRFY((hrc >= 0), "H5Sselect_hyperslab");
-		} /* end if */
-		else {
-		    h5dset_space_id = H5Screate(H5S_SCALAR);
-		    VRFY((h5dset_space_id >= 0), "H5Screate");
-		} /* end else */
-
-		/* Create the memory dataspace that corresponds to the xfer buffer */
-		if(buf_size>0) {
-		    h5dims[0] = buf_size;
-		    h5mem_space_id = H5Screate_simple(1, h5dims, NULL);
-		    VRFY((h5mem_space_id >= 0), "H5Screate_simple");
-		} /* end if */
-		else {
-		    h5mem_space_id = H5Screate(H5S_SCALAR);
-		    VRFY((h5mem_space_id >= 0), "H5Screate");
-		} /* end else */
-	    } /* end if */
-	    /* 2D dataspace */
-	    else {
-		if(nbytes>0) {
-		    /* define a contiguous dataset of nbytes native bytes */
-		    h5dims[0] = snbytes;
-		    h5dims[1] = snbytes;
-		    h5dset_space_id = H5Screate_simple(2, h5dims, NULL);
-		    VRFY((h5dset_space_id >= 0), "H5Screate_simple");
-
-		    /* Set up the file dset space id to select the pattern to access */
-		    if (parms->interleaved==0){
-			/* Contiguous pattern */
-			h5start[0] = bytes_begin[0];
-			h5start[1] = bytes_begin[1];
-			h5stride[0] = 1;
-			h5stride[1] = h5block[0] = h5block[1] = blk_size;
-			h5count[0] = 1;
-			h5count[1] = buf_size/blk_size;
-		    } /* end if */
-		    else {
-			/* Interleaved access pattern */
-			/* Skip offset over blocks of other processes */
-			h5start[0] = bytes_begin[0];
-			h5start[1] = bytes_begin[1];
-			h5stride[0] = blk_size;
-			h5stride[1] = blk_size*pio_mpi_nprocs_g;
-			h5block[0] = h5block[1] = blk_size;
-			h5count[0] = buf_size/blk_size;
-			h5count[1] = 1;
-		    } /* end else */
-		    hrc = H5Sselect_hyperslab(h5dset_space_id, H5S_SELECT_SET,
-			    h5start, h5stride, h5count, h5block);
-		    VRFY((hrc >= 0), "H5Sselect_hyperslab");
-		} /* end if */
-		else {
-		    h5dset_space_id = H5Screate(H5S_SCALAR);
-		    VRFY((h5dset_space_id >= 0), "H5Screate");
-		} /* end else */
-
-		/* Create the memory dataspace that corresponds to the xfer buffer */
-		if(buf_size>0) {
-		    if (parms->interleaved==0){
-			h5dims[0] = blk_size;
-			h5dims[1] = buf_size;
-		    }else{
-			h5dims[0] = buf_size;
-			h5dims[1] = blk_size;
-		    }
-		    h5mem_space_id = H5Screate_simple(2, h5dims, NULL);
-		    VRFY((h5mem_space_id >= 0), "H5Screate_simple");
-		} /* end if */
-		else {
-		    h5mem_space_id = H5Screate(H5S_SCALAR);
-		    VRFY((h5mem_space_id >= 0), "H5Screate");
-		} /* end else */
-	    } /* end else */
-
-	    /* Create the dataset transfer property list */
-	    h5dxpl = H5Pcreate(H5P_DATASET_XFER);
-	    if (h5dxpl < 0) {
-		fprintf(stderr, "HDF5 Property List Create failed\n");
-		GOTOERROR(FAIL);
-	    }
-
-	    /* Change to collective I/O, if asked */
-	    if(parms->collective) {
-		hrc = H5Pset_dxpl_mpio(h5dxpl, H5FD_MPIO_COLLECTIVE);
-		if (hrc < 0) {
-		    fprintf(stderr, "HDF5 Property List Set failed\n");
-		    GOTOERROR(FAIL);
-		} /* end if */
-	    } /* end if */
-	    break;
+    case POSIXIO:
+        /* No extra setup */
+        break;
+
+    case MPIO: /* MPI-I/O setup */
+        /* 1D dataspace */
+        if (!parms->dim2d){
+            /* Build block's derived type */
+            mrc = MPI_Type_contiguous((int)blk_size,
+                MPI_BYTE, &mpi_blk_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Build file's derived type */
+            mrc = MPI_Type_vector((int)(buf_size/blk_size), (int)1,
+                (int)pio_mpi_nprocs_g, mpi_blk_type, &mpi_file_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Commit file type */
+            mrc = MPI_Type_commit( &mpi_file_type );
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+
+            /* Commit buffer type */
+            mrc = MPI_Type_commit( &mpi_blk_type );
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+        } /* end if */
+        /* 2D dataspace */
+        else {
+            /* Build partial buffer derived type for contiguous access */
+
+            mrc = MPI_Type_contiguous((int)buf_size, MPI_BYTE,
+                &mpi_partial_buffer_cont);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Commit partial buffer derived type */
+            mrc = MPI_Type_commit(&mpi_partial_buffer_cont);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+            
+            /* Build contiguous file's derived type */
+            mrc = MPI_Type_vector((int)blk_size, (int)1, (int)(snbytes/buf_size),
+                mpi_partial_buffer_cont, &mpi_cont_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Commit contiguous file type */
+            mrc = MPI_Type_commit(&mpi_cont_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+
+            /* Build partial buffer derived type for interleaved access */
+            mrc = MPI_Type_contiguous((int)blk_size, MPI_BYTE,
+                &mpi_partial_buffer_inter);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Commit partial buffer derived type */
+            mrc = MPI_Type_commit(&mpi_partial_buffer_inter);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+
+            /* Build interleaved file's derived type */
+            mrc = MPI_Type_vector((int)buf_size, (int)1, (int)(snbytes/blk_size),
+                mpi_partial_buffer_inter, &mpi_inter_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Commit interleaved file type */
+            mrc = MPI_Type_commit(&mpi_inter_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+
+            /* Build full buffer derived type */
+            mrc = MPI_Type_contiguous((int)(blk_size*buf_size), MPI_BYTE,
+                &mpi_full_buffer);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Commit full buffer derived type */
+            mrc = MPI_Type_commit(&mpi_full_buffer);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+
+            /* Build full chunk derived type */               
+            mrc = MPI_Type_contiguous((int)(blk_size*blk_size), MPI_BYTE,
+                &mpi_full_chunk);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Commit full chunk derived type */
+            mrc = MPI_Type_commit(&mpi_full_chunk);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+
+            /* Build chunk interleaved file's derived type */             
+            mrc = MPI_Type_vector((int)(buf_size/blk_size), (int)1, (int)(snbytes/blk_size),
+                mpi_full_chunk, &mpi_chunk_inter_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Commit chunk interleaved file type */
+            mrc = MPI_Type_commit(&mpi_chunk_inter_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+
+        } /* end else */
+        break;
+
+    case PHDF5: /* HDF5 setup */
+        /* 1D dataspace */
+        if (!parms->dim2d){
+            if(nbytes>0) {
+                /* define a contiguous dataset of nbytes native bytes */
+                h5dims[0] = nbytes;
+                h5dset_space_id = H5Screate_simple(1, h5dims, NULL);
+                VRFY((h5dset_space_id >= 0), "H5Screate_simple");
+
+                /* Set up the file dset space id to select the pattern to access */
+                if (!parms->interleaved){
+                /* Contiguous pattern */
+                h5start[0] = bytes_begin[0];
+                h5stride[0] = h5block[0] = blk_size;
+                h5count[0] = buf_size/blk_size;
+                } /* end if */
+                else {
+                /* Interleaved access pattern */
+                /* Skip offset over blocks of other processes */
+                h5start[0] = bytes_begin[0];
+                h5stride[0] = blk_size*pio_mpi_nprocs_g;
+                h5block[0] = blk_size;
+                h5count[0] = buf_size/blk_size;
+                } /* end else */
+                hrc = H5Sselect_hyperslab(h5dset_space_id, H5S_SELECT_SET,
+                    h5start, h5stride, h5count, h5block);
+                VRFY((hrc >= 0), "H5Sselect_hyperslab");
+            } /* end if */
+            else {
+                h5dset_space_id = H5Screate(H5S_SCALAR);
+                VRFY((h5dset_space_id >= 0), "H5Screate");
+            } /* end else */
+
+            /* Create the memory dataspace that corresponds to the xfer buffer */
+            if(buf_size>0) {
+                h5dims[0] = buf_size;
+                h5mem_space_id = H5Screate_simple(1, h5dims, NULL);
+                VRFY((h5mem_space_id >= 0), "H5Screate_simple");
+            } /* end if */
+            else {
+                h5mem_space_id = H5Screate(H5S_SCALAR);
+                VRFY((h5mem_space_id >= 0), "H5Screate");
+            } /* end else */
+        } /* end if */
+        /* 2D dataspace */
+        else {
+            if(nbytes>0) {
+                /* define a contiguous dataset of nbytes native bytes */
+                h5dims[0] = snbytes;
+                h5dims[1] = snbytes;
+                h5dset_space_id = H5Screate_simple(2, h5dims, NULL);
+                VRFY((h5dset_space_id >= 0), "H5Screate_simple");
+
+                /* Set up the file dset space id to select the pattern to access */
+                if (!parms->interleaved){
+                /* Contiguous pattern */
+                h5start[0] = bytes_begin[0];
+                h5start[1] = bytes_begin[1];
+                h5stride[0] = 1;
+                h5stride[1] = h5block[0] = h5block[1] = blk_size;
+                h5count[0] = 1;
+                h5count[1] = buf_size/blk_size;
+                } /* end if */
+                else {
+                /* Interleaved access pattern */
+                /* Skip offset over blocks of other processes */
+                h5start[0] = bytes_begin[0];
+                h5start[1] = bytes_begin[1];
+                h5stride[0] = blk_size;
+                h5stride[1] = blk_size*pio_mpi_nprocs_g;
+                h5block[0] = h5block[1] = blk_size;
+                h5count[0] = buf_size/blk_size;
+                h5count[1] = 1;
+                } /* end else */
+                hrc = H5Sselect_hyperslab(h5dset_space_id, H5S_SELECT_SET,
+                    h5start, h5stride, h5count, h5block);
+                VRFY((hrc >= 0), "H5Sselect_hyperslab");
+            } /* end if */
+            else {
+                h5dset_space_id = H5Screate(H5S_SCALAR);
+                VRFY((h5dset_space_id >= 0), "H5Screate");
+            } /* end else */
+
+            /* Create the memory dataspace that corresponds to the xfer buffer */
+            if(buf_size>0) {
+                if (!parms->interleaved){
+                h5dims[0] = blk_size;
+                h5dims[1] = buf_size;
+                }else{
+                h5dims[0] = buf_size;
+                h5dims[1] = blk_size;
+                }
+                h5mem_space_id = H5Screate_simple(2, h5dims, NULL);
+                VRFY((h5mem_space_id >= 0), "H5Screate_simple");
+            } /* end if */
+            else {
+                h5mem_space_id = H5Screate(H5S_SCALAR);
+                VRFY((h5mem_space_id >= 0), "H5Screate");
+            } /* end else */
+        } /* end else */
+
+        /* Create the dataset transfer property list */
+        h5dxpl = H5Pcreate(H5P_DATASET_XFER);
+        if (h5dxpl < 0) {
+        fprintf(stderr, "HDF5 Property List Create failed\n");
+        GOTOERROR(FAIL);
+        }
+
+        /* Change to collective I/O, if asked */
+        if(parms->collective) {
+            hrc = H5Pset_dxpl_mpio(h5dxpl, H5FD_MPIO_COLLECTIVE);
+            if (hrc < 0) {
+                fprintf(stderr, "HDF5 Property List Set failed\n");
+                GOTOERROR(FAIL);
+            } /* end if */
+        } /* end if */
+        break;
     } /* end switch */
 
     for (ndset = 1; ndset <= ndsets; ++ndset) {
 
-	/* Calculate dataset offset within a file */
-
-	/* create dataset */
-	switch (parms->io_type) {
-	    case POSIXIO:
-	    case MPIO:
-		/* both posix and mpi io just need dataset offset in file*/
-		dset_offset = (ndset - 1) * nbytes;
-		break;
-
-	    case PHDF5:
-		h5dcpl = H5Pcreate(H5P_DATASET_CREATE);
-		if (h5dcpl < 0) {
-		    fprintf(stderr, "HDF5 Property List Create failed\n");
-		    GOTOERROR(FAIL);
-		}
-		/* 1D dataspace */
-		if (parms->dim2d==0){
-		    /* Make the dataset chunked if asked */
-		    if(parms->h5_use_chunks) {
-			/* Set the chunk size to be the same as the buffer size */
-			h5dims[0] = blk_size;
-			hrc = H5Pset_chunk(h5dcpl, 1, h5dims);
-			if (hrc < 0) {
-			    fprintf(stderr, "HDF5 Property List Set failed\n");
-			    GOTOERROR(FAIL);
-			} /* end if */
-		    } /* end if */
-		}/* end if */
-		else{
-		    /* 2D dataspace */
-		    if(parms->h5_use_chunks) {
-			/* Set the chunk size to be the same as the block size */
-			h5dims[0] = blk_size;
-			h5dims[1] = blk_size;
-			hrc = H5Pset_chunk(h5dcpl, 2, h5dims);
-			if (hrc < 0) {
-			    fprintf(stderr, "HDF5 Property List Set failed\n");
-			    GOTOERROR(FAIL);
-			} /* end if */
-		    } /* end if */
-		}/* end else */
-
-		sprintf(dname, "Dataset_%ld", ndset);
-		h5ds_id = H5Dcreate2(fd->h5fd, dname, ELMT_H5_TYPE,
-			h5dset_space_id, H5P_DEFAULT, h5dcpl, H5P_DEFAULT);
-
-		if(h5ds_id < 0) {
-		    fprintf(stderr, "HDF5 Dataset Create failed\n");
-		    GOTOERROR(FAIL);
-		}
-
-		hrc = H5Pclose(h5dcpl);
-		/* verifying the close of the dcpl */
-		if(hrc < 0) {
-		    fprintf(stderr, "HDF5 Property List Close failed\n");
-		    GOTOERROR(FAIL);
-		}
-
-		break;
-	}
-
-	/* The task is to transfer bytes_count bytes, starting at
-	 * bytes_begin position, using transfer buffer of buf_size bytes.
-	 * If interleaved, select buf_size at a time, in round robin
-	 * fashion, according to number of process. Otherwise, select
-	 * all bytes_count in contiguous.
-	 */
-	nbytes_xfer = 0 ;
-
-	/* 1D dataspace */
-	if (parms->dim2d==0){
-	    /* Set base file offset for all I/O patterns and POSIX access */
-	    posix_file_offset = dset_offset + bytes_begin[0];
-
-	    /* Set base file offset for all I/O patterns and MPI access */
-	    mpi_file_offset = (MPI_Offset)(dset_offset + bytes_begin[0]);
-	} /* end if */
-	else {
-	    /* Set base file offset for all I/O patterns and POSIX access */
-	    posix_file_offset=dset_offset + bytes_begin[0]*snbytes+
-		bytes_begin[1];
-
-	    /* Set base file offset for all I/O patterns and MPI access */
-	    mpi_file_offset=(MPI_Offset)(dset_offset + bytes_begin[0]*snbytes+
-		    bytes_begin[1]);
-	} /* end else */
-
-	/* Start "raw data" write timer */
-	set_time(res->timers, HDF5_RAW_WRITE_FIXED_DIMS, START);
-
-	while (nbytes_xfer < bytes_count){
-	    /* Write */
-	    /* Calculate offset of write within a dataset/file */
-	    switch (parms->io_type) {
-		case POSIXIO:
-		    /* 1D dataspace */
-		    if (parms->dim2d==0){
-			/* Contiguous pattern */
-			if (parms->interleaved==0) {
-			    /* Compute file offset */
-			    file_offset = posix_file_offset + (off_t)nbytes_xfer;
-
-			    /* only care if seek returns error */
-			    rc = POSIXSEEK(fd->posixfd, file_offset) < 0 ? -1 : 0;
-			    VRFY((rc==0), "POSIXSEEK");
-
-			    /* check if all bytes are written */
-			    rc = ((ssize_t)buf_size ==
-				    POSIXWRITE(fd->posixfd, buffer, buf_size));
-			    VRFY((rc != 0), "POSIXWRITE");
-
-			    /* Advance global offset in dataset */
-			    nbytes_xfer+=buf_size;
-			} /* end if */
-			/* Interleaved access pattern */
-			else {
-			    /* Set the base of user's buffer */
-			    buf_p=(unsigned char *)buffer;
-
-			    /* Set the number of bytes to transfer this time */
-			    nbytes_toxfer = buf_size;
-
-			    /* Loop over the buffers to write */
-			    while(nbytes_toxfer>0) {
-				/* Skip offset over blocks of other processes */
-				file_offset = posix_file_offset +
-				    (off_t)(nbytes_xfer*pio_mpi_nprocs_g);
-
-				/* only care if seek returns error */
-				rc = POSIXSEEK(fd->posixfd, file_offset) < 0 ? -1 : 0;
-				VRFY((rc==0), "POSIXSEEK");
-
-				/* check if all bytes are written */
-				rc = ((ssize_t)blk_size ==
-					POSIXWRITE(fd->posixfd, buf_p, blk_size));
-				VRFY((rc != 0), "POSIXWRITE");
-
-				/* Advance location in buffer */
-				buf_p+=blk_size;
-
-				/* Advance global offset in dataset */
-				nbytes_xfer+=blk_size;
-
-				/* Decrement number of bytes left this time */
-				nbytes_toxfer-=blk_size;
-			    } /* end while */
-			} /* end else */
-		    } /* end if */
-		    /* 2D dataspace */
-		    else {
-			/* Contiguous pattern */
-			if (parms->interleaved==0){
-			    /* Set the base of user's buffer */
-			    buf_p = (unsigned char *)buffer;
-
-			    /* Set the number of bytes to transfer this time */
-			    nbytes_toxfer = buf_size*blk_size;
-
-			    /* Compute file offset */
-			    file_offset=posix_file_offset+(off_t)(((nbytes_xfer/blk_size)/(snbytes))*
-				    (blk_size*snbytes)+((nbytes_xfer/blk_size)%(snbytes)));
-
-			    /* Loop over portions of the buffer to write */
-			    while(nbytes_toxfer>0){
-				/* only care if seek returns error */
-				rc = POSIXSEEK(fd->posixfd, file_offset) < 0 ? -1 : 0;
-				VRFY((rc==0), "POSIXSEEK");
-
-				/* check if all bytes are written */
-				rc = ((ssize_t)buf_size ==
-					POSIXWRITE(fd->posixfd, buffer, buf_size));
-				VRFY((rc != 0), "POSIXWRITE");
-
-				/* Advance location in buffer */
-				buf_p+=buf_size;
-
-				/* Advance global offset in dataset */
-				nbytes_xfer+=buf_size;
-
-				/* Decrement number of bytes left this time */
-				nbytes_toxfer-=buf_size;
-
-				/* Partially advance file offset */
-				file_offset+=(off_t)(snbytes);
-			    } /* end while */
-			} /* end if */
-			/* Interleaved access pattern */
-			else{
-			    /* Set the base of user's buffer */
-			    buf_p=(unsigned char *)buffer;
-
-			    /* Set the number of bytes to transfer this time */
-			    nbytes_toxfer=buf_size*blk_size;
-
-			    /* Compute file offset */
-			    file_offset=posix_file_offset+(off_t)(((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)/(snbytes)*
-				    (buf_size*snbytes)+((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)%(snbytes));
-
-			    /* Loop over portions of the buffer to write */
-			    while(nbytes_toxfer>0){
-				/* only care if seek returns error */
-				rc = POSIXSEEK(fd->posixfd, file_offset) < 0 ? -1 : 0;
-				VRFY((rc==0), "POSIXSEEK");
-
-				/* check if all bytes are written */
-				rc = ((ssize_t)blk_size ==
-					POSIXWRITE(fd->posixfd, buffer, blk_size));
-				VRFY((rc != 0), "POSIXWRITE");
-
-				/* Advance location in buffer */
-				buf_p+=blk_size;
-
-				/* Advance global offset in dataset */
-				nbytes_xfer+=blk_size;
-
-				/* Decrement number of bytes left this time */
-				nbytes_toxfer-=blk_size;
-
-				/* Partially advance file offset */
-				file_offset+=(off_t)(snbytes);
-			    } /* end while */
-			}/* end else */
-		    } /* end else */
-		    break;
-
-		case MPIO:
-		    /* 1D dataspace */
-		    if (parms->dim2d==0){
-			/* Independent file access */
-			if(parms->collective==0) {
-			    /* Contiguous pattern */
-			    if (parms->interleaved==0){
-				/* Compute offset in file */
-				mpi_offset = mpi_file_offset +
-				    nbytes_xfer;
-
-				/* Perform independent write */
-				mrc = MPI_File_write_at(fd->mpifd, mpi_offset, buffer,
-					(int)(buf_size/blk_size), mpi_blk_type,
-					&mpi_status);
-				VRFY((mrc==MPI_SUCCESS), "MPIO_WRITE");
-
-				/* Advance global offset in dataset */
-				nbytes_xfer+=buf_size;
-			    } /* end if */
-			    /* Interleaved access pattern */
-			    else {
-				/* Set the base of user's buffer */
-				buf_p=(unsigned char *)buffer;
-
-				/* Set the number of bytes to transfer this time */
-				nbytes_toxfer = buf_size;
-
-				/* Loop over the buffers to write */
-				while(nbytes_toxfer>0) {
-				    /* Skip offset over blocks of other processes */
-				    mpi_offset = mpi_file_offset +
-					(nbytes_xfer*pio_mpi_nprocs_g);
-
-				    /* Perform independent write */
-				    mrc = MPI_File_write_at(fd->mpifd, mpi_offset, buf_p,
-					    (int)1, mpi_blk_type, &mpi_status);
-				    VRFY((mrc==MPI_SUCCESS), "MPIO_WRITE");
-
-				    /* Advance location in buffer */
-				    buf_p+=blk_size;
-
-				    /* Advance global offset in dataset */
-				    nbytes_xfer+=blk_size;
-
-				    /* Decrement number of bytes left this time */
-				    nbytes_toxfer-=blk_size;
-				} /* end while */
-			    } /* end else */
-			} /* end if */
-			/* Collective file access */
-			else {
-			    /* Contiguous access pattern */
-			    if (parms->interleaved==0){
-				/* Compute offset in file */
-				mpi_offset = mpi_file_offset +
-				    nbytes_xfer;
-
-				/* Perform independent write */
-				mrc = MPI_File_write_at_all(fd->mpifd, mpi_offset, buffer,
-					(int)(buf_size/blk_size), mpi_blk_type, &mpi_status);
-				VRFY((mrc==MPI_SUCCESS), "MPIO_WRITE");
-
-				/* Advance global offset in dataset */
-				nbytes_xfer+=buf_size;
-			    } /* end if */
-			    /* Interleaved access pattern */
-			    else {
-				/* Compute offset in file */
-				mpi_offset = mpi_file_offset +
-				    (nbytes_xfer*pio_mpi_nprocs_g);
-
-				/* Set the file view */
-				mrc = MPI_File_set_view(fd->mpifd, mpi_offset, mpi_blk_type,
-					mpi_file_type, (char*)"native",  h5_io_info_g);
-				VRFY((mrc==MPI_SUCCESS), "MPIO_VIEW");
-
-				/* Perform write */
-				mrc = MPI_File_write_at_all(fd->mpifd, 0, buffer,
-					(int)(buf_size/blk_size), mpi_blk_type, &mpi_status);
-				VRFY((mrc==MPI_SUCCESS), "MPIO_WRITE");
-
-				/* Advance global offset in dataset */
-				nbytes_xfer+=buf_size;
-			    } /* end else */
-			} /* end else */
-		    } /* end if */
-		    /* 2D dataspace */
-		    else {
-			/* Independent file access */
-			if (parms->collective==0)
-			    /* Contiguous pattern */
-			    if (parms->interleaved==0){
-				/* Set the base of user's buffer */
-				buf_p = (unsigned char *)buffer;
-
-				/* Set the number of bytes to transfer this time */
-				nbytes_toxfer = buf_size*blk_size;
-
-				/* Compute offset in file */
-				mpi_offset=mpi_file_offset+((nbytes_xfer/blk_size)/(snbytes))*
-				    (blk_size*snbytes)+((nbytes_xfer/blk_size)%(snbytes));
-
-				/* Loop over portions of the buffer to write */
-				while(nbytes_toxfer>0){
-
-				    /* Perform independent write */
-				    mrc = MPI_File_write_at(fd->mpifd, mpi_offset, buf_p, (int)buf_size, MPI_BYTE, &mpi_status);
-				    VRFY((mrc==MPI_SUCCESS), "MPIO_WRITE");
-
-				    /* Advance location in buffer */
-				    buf_p+=buf_size;
-
-				    /* Advance global offset in dataset */
-				    nbytes_xfer+=buf_size;
-
-				    /* Decrement number of bytes left this time */
-				    nbytes_toxfer-=buf_size;
-
-				    /* Partially advance global offset in dataset */
-				    mpi_offset+=snbytes;
-				} /* end while */
-			    } /* end if */
-			/* Interleaved access pattern */
-			    else{
-				/* Set the base of user's buffer */
-				buf_p=(unsigned char *)buffer;
-
-				/* Set the number of bytes to transfer this time */
-				nbytes_toxfer=buf_size*blk_size;
-
-				/* Compute offset in file */
-				mpi_offset=mpi_file_offset+((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)/(snbytes)*
-				    (buf_size*snbytes)+((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)%(snbytes);
-
-				/* Loop over portions of the buffer to write */
-				while(nbytes_toxfer>0){
-				    /* Perform independent write */
-				    mrc = MPI_File_write_at(fd->mpifd, mpi_offset, buf_p, (int)blk_size, MPI_BYTE, &mpi_status);
-				    VRFY((mrc==MPI_SUCCESS), "MPIO_WRITE");
-
-				    /* Advance location in buffer */
-				    buf_p+=blk_size;
-
-				    /* Advance global offset in dataset */
-				    nbytes_xfer+=blk_size;
-
-				    /* Decrement number of bytes left this time */
-				    nbytes_toxfer-=blk_size;
-
-				    /* Partially advance global offset in dataset */
-				    mpi_offset+=snbytes;
-				} /* end while */
-			    } /* end else */
-			/* end if */
-			/* Collective file access */
-			else
-			    /* Contiguous access pattern */
-			    if (parms->interleaved==0){
-				/* Compute offset in file */
-				mpi_offset=mpi_file_offset+((nbytes_xfer/blk_size)/(snbytes))*
-				    (blk_size*snbytes)+((nbytes_xfer/blk_size)%(snbytes));
-
-				/* Set the file view */
-				mrc = MPI_File_set_view(fd->mpifd, mpi_offset, MPI_BYTE, mpi_cont_type, (char *)"native", h5_io_info_g);
-				VRFY((mrc==MPI_SUCCESS), "MPIO_VIEW");
-
-				/* Perform write */
-				MPI_File_write_at_all(fd->mpifd, 0, buffer,(int)(buf_size*blk_size),MPI_BYTE, &mpi_status);
-				VRFY((mrc==MPI_SUCCESS), "MPIO_WRITE");
-
-				nbytes_xfer+=buf_size*blk_size;
-			    } /* end if */
-			/* Interleaved access pattern */
-			    else{
-				/* Compute offset in file */
-				mpi_offset=mpi_file_offset+((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)/(snbytes)*
-				    (buf_size*snbytes)+((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)%(snbytes);
-
-				/* Set the file view */
-				mrc = MPI_File_set_view(fd->mpifd, mpi_offset, MPI_BYTE, mpi_inter_type, (char *)"native", h5_io_info_g);
-				VRFY((mrc==MPI_SUCCESS), "MPIO_VIEW");
-
-				/* Perform write */
-				MPI_File_write_at_all(fd->mpifd, 0, buffer, (int)(buf_size*blk_size), MPI_BYTE, &mpi_status);
-				VRFY((mrc==MPI_SUCCESS), "MPIO_WRITE");
-
-				nbytes_xfer+=buf_size*blk_size;
-			    } /* end else */
-			/* end else */
-		    } /* end else */
-		    break;
-
-		case PHDF5:
-		    /* 1D dataspace */
-		    if (parms->dim2d==0){
-			/* Set up the file dset space id to move the selection to process */
-			if (parms->interleaved==0){
-			    /* Contiguous pattern */
-			    h5offset[0] = nbytes_xfer;
-			} /* end if */
-			else {
-			    /* Interleaved access pattern */
-			    /* Skip offset over blocks of other processes */
-			    h5offset[0] = (nbytes_xfer*pio_mpi_nprocs_g);
-			} /* end else */
-			hrc = H5Soffset_simple(h5dset_space_id, h5offset);
-			VRFY((hrc >= 0), "H5Soffset_simple");
-
-			/* Write the buffer out */
-			hrc = H5Dwrite(h5ds_id, ELMT_H5_TYPE, h5mem_space_id,
-				h5dset_space_id, h5dxpl, buffer);
-			VRFY((hrc >= 0), "H5Dwrite");
-
-			/* Increment number of bytes transferred */
-			nbytes_xfer += buf_size;
-		    } /* end if */
-		    /* 2D dataspace */
-		    else {
-			/* Set up the file dset space id to move the selection to process */
-			if (parms->interleaved==0){
-			    /* Contiguous pattern */
-			    h5offset[0] = (nbytes_xfer/(snbytes*blk_size))*blk_size;
-			    h5offset[1] = (nbytes_xfer%(snbytes*blk_size))/blk_size;
-
-			} /* end if */
-			else {
-			    /* Interleaved access pattern */
-			    /* Skip offset over blocks of other processes */
-			    h5offset[0] = ((nbytes_xfer*pio_mpi_nprocs_g)/(snbytes*buf_size))*buf_size;
-			    h5offset[1] = ((nbytes_xfer*pio_mpi_nprocs_g)%(snbytes*buf_size))/buf_size;
-
-			} /* end else */
-			hrc = H5Soffset_simple(h5dset_space_id, h5offset);
-			VRFY((hrc >= 0), "H5Soffset_simple");
-
-			/* Write the buffer out */
-			hrc = H5Dwrite(h5ds_id, ELMT_H5_TYPE, h5mem_space_id,
-				h5dset_space_id, h5dxpl, buffer);
-			VRFY((hrc >= 0), "H5Dwrite");
-
-			/* Increment number of bytes transferred */
-			nbytes_xfer += buf_size*blk_size;
-
-		    } /* end else */
-
-		    break;
-	    } /* switch (parms->io_type) */
-	} /* end while */
-
-	/* Stop "raw data" write timer */
-	set_time(res->timers, HDF5_RAW_WRITE_FIXED_DIMS, STOP);
-
-	/* Calculate write time */
-
-	/* Close dataset. Only HDF5 needs to do an explicit close. */
-	if (parms->io_type == PHDF5) {
-	    hrc = H5Dclose(h5ds_id);
-
-	    if (hrc < 0) {
-		fprintf(stderr, "HDF5 Dataset Close failed\n");
-		GOTOERROR(FAIL);
-	    }
-
-	    h5ds_id = -1;
-	} /* end if */
+    /* Calculate dataset offset within a file */
+
+    /* create dataset */
+    switch (parms->io_type) {
+        case POSIXIO:
+        case MPIO:
+        /* both posix and mpi io just need dataset offset in file*/
+        dset_offset = (ndset - 1) * nbytes;
+        break;
+
+        case PHDF5:
+        h5dcpl = H5Pcreate(H5P_DATASET_CREATE);
+        if (h5dcpl < 0) {
+            fprintf(stderr, "HDF5 Property List Create failed\n");
+            GOTOERROR(FAIL);
+        }
+        /* 1D dataspace */
+        if (!parms->dim2d){
+            /* Make the dataset chunked if asked */
+            if(parms->h5_use_chunks) {
+            /* Set the chunk size to be the same as the buffer size */
+            h5dims[0] = blk_size;
+            hrc = H5Pset_chunk(h5dcpl, 1, h5dims);
+            if (hrc < 0) {
+                fprintf(stderr, "HDF5 Property List Set failed\n");
+                GOTOERROR(FAIL);
+            } /* end if */
+            } /* end if */
+        }/* end if */
+        else{
+            /* 2D dataspace */
+            if(parms->h5_use_chunks) {
+            /* Set the chunk size to be the same as the block size */
+            h5dims[0] = blk_size;
+            h5dims[1] = blk_size;
+            hrc = H5Pset_chunk(h5dcpl, 2, h5dims);
+            if (hrc < 0) {
+                fprintf(stderr, "HDF5 Property List Set failed\n");
+                GOTOERROR(FAIL);
+            } /* end if */
+            } /* end if */
+        }/* end else */
+
+        sprintf(dname, "Dataset_%ld", ndset);
+        h5ds_id = H5Dcreate2(fd->h5fd, dname, ELMT_H5_TYPE,
+            h5dset_space_id, H5P_DEFAULT, h5dcpl, H5P_DEFAULT);
+
+        if (h5ds_id < 0) {
+            fprintf(stderr, "HDF5 Dataset Create failed\n");
+            GOTOERROR(FAIL);
+        }
+
+        hrc = H5Pclose(h5dcpl);
+        /* verifying the close of the dcpl */
+        if (hrc < 0) {
+            fprintf(stderr, "HDF5 Property List Close failed\n");
+            GOTOERROR(FAIL);
+        }
+
+        break;
+    }
+
+    /* The task is to transfer bytes_count bytes, starting at
+     * bytes_begin position, using transfer buffer of buf_size bytes.
+     * If interleaved, select buf_size at a time, in round robin
+     * fashion, according to number of process. Otherwise, select
+     * all bytes_count in contiguous.
+     */
+    nbytes_xfer = 0 ;
+
+    /* 1D dataspace */
+    if (!parms->dim2d){
+        /* Set base file offset for all I/O patterns and POSIX access */
+        posix_file_offset = dset_offset + bytes_begin[0];
+
+        /* Set base file offset for all I/O patterns and MPI access */
+        mpi_file_offset = (MPI_Offset)(dset_offset + bytes_begin[0]);
+    } /* end if */
+    else {
+        /* Set base file offset for all I/O patterns and POSIX access */
+        posix_file_offset=dset_offset + bytes_begin[0]*snbytes+
+        bytes_begin[1];
+
+        /* Set base file offset for all I/O patterns and MPI access */
+        mpi_file_offset=(MPI_Offset)(dset_offset + bytes_begin[0]*snbytes+
+            bytes_begin[1]);
+    } /* end else */
+
+    /* Start "raw data" write timer */
+    set_time(res->timers, HDF5_RAW_WRITE_FIXED_DIMS, START);
+
+    while (nbytes_xfer < bytes_count){
+        /* Write */
+        /* Calculate offset of write within a dataset/file */
+        switch (parms->io_type) {
+        case POSIXIO:
+            /* 1D dataspace */
+            if (!parms->dim2d){
+                /* Contiguous pattern */
+                if (!parms->interleaved) {
+                    /* Compute file offset */
+                    file_offset = posix_file_offset + (off_t)nbytes_xfer;
+
+                    /* only care if seek returns error */
+                    rc = POSIXSEEK(fd->posixfd, file_offset) < 0 ? -1 : 0;
+                    VRFY((rc==0), "POSIXSEEK");
+
+                    /* check if all bytes are written */
+                    rc = ((ssize_t)buf_size ==
+                        POSIXWRITE(fd->posixfd, buffer, buf_size));
+                    VRFY((rc != 0), "POSIXWRITE");
+
+                    /* Advance global offset in dataset */
+                    nbytes_xfer+=buf_size;
+                } /* end if */
+                /* Interleaved access pattern */
+                else {
+                    /* Set the base of user's buffer */
+                    buf_p=(unsigned char *)buffer;
+
+                    /* Set the number of bytes to transfer this time */
+                    nbytes_toxfer = buf_size;
+
+                    /* Loop over the buffers to write */
+                    while(nbytes_toxfer>0) {
+                        /* Skip offset over blocks of other processes */
+                        file_offset = posix_file_offset +
+                            (off_t)(nbytes_xfer*pio_mpi_nprocs_g);
+
+                        /* only care if seek returns error */
+                        rc = POSIXSEEK(fd->posixfd, file_offset) < 0 ? -1 : 0;
+                        VRFY((rc==0), "POSIXSEEK");
+
+                        /* check if all bytes are written */
+                        rc = ((ssize_t)blk_size ==
+                            POSIXWRITE(fd->posixfd, buf_p, blk_size));
+                        VRFY((rc != 0), "POSIXWRITE");
+
+                        /* Advance location in buffer */
+                        buf_p+=blk_size;
+
+                        /* Advance global offset in dataset */
+                        nbytes_xfer+=blk_size;
+
+                        /* Decrement number of bytes left this time */
+                        nbytes_toxfer-=blk_size;
+                    } /* end while */
+                } /* end else */
+            } /* end if */
+            /* 2D dataspace */
+            else {
+                /* Contiguous storage */
+                if (!parms->h5_use_chunks) {
+                    /* Contiguous access pattern */
+                    if (!parms->interleaved) {
+                        /* Compute file offset */
+                        file_offset=posix_file_offset+(off_t)(((nbytes_xfer/blk_size)
+                            /snbytes)*(blk_size*snbytes)+((nbytes_xfer/blk_size)%snbytes));
+
+                        /* Number of bytes to be transferred per I/O operation */
+                        nbytes_xfer_advance = buf_size;
+
+                        /* Global offset advance after each I/O operation */                            
+                        file_offset_advance = (off_t)snbytes;
+                    } /* end if */
+                    /* Interleaved access pattern */
+                    else {
+                        /* Compute file offset */
+                        file_offset=posix_file_offset+(off_t)((((nbytes_xfer/buf_size)
+                            *pio_mpi_nprocs_g)/snbytes)*(buf_size*snbytes)
+                            +((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)%snbytes);
+
+                        /* Number of bytes to be transferred per I/O operation */
+                        nbytes_xfer_advance = blk_size;
+
+                        /* Global offset advance after each I/O operation */                            
+                        file_offset_advance = (off_t)snbytes;
+                    } /* end else */
+                } /* end if */
+                /* Chunked storage */
+                else {
+                    /*Contiguous access pattern */
+                    if (!parms->interleaved) {
+                        /* Compute file offset */
+                        file_offset=posix_file_offset+(off_t)nbytes_xfer;
+
+                        /* Number of bytes to be transferred per I/O operation */
+                        nbytes_xfer_advance = blk_size * buf_size;
+
+                        /* Global offset advance after each I/O operation */                            
+                        file_offset_advance = 0;
+                    } /* end if */
+                    /*Interleaved access pattern */
+                    else {
+                        /* Compute file offset */
+                        /* Before simplification */
+                        /* file_offset=posix_file_offset+(off_t)((nbytes_xfer/(buf_size/blk_size)
+                        *pio_mpi_nprocs_g)/(snbytes/blk_size*(blk_size*blk_size))*(buf_size/blk_size
+                        *snbytes/blk_size*(blk_size*blk_size))+((nbytes_xfer/(buf_size/blk_size))
+                        *pio_mpi_nprocs_g)%(snbytes/blk_size*(blk_size*blk_size))); */
+
+                        file_offset=posix_file_offset+(off_t)(((nbytes_xfer/(buf_size/blk_size)
+                        *pio_mpi_nprocs_g)/(snbytes*blk_size))*(buf_size*snbytes)+((nbytes_xfer/(buf_size/blk_size))
+                        *pio_mpi_nprocs_g)%(snbytes*blk_size));
+
+                        /* Number of bytes to be transferred per I/O operation */
+                        nbytes_xfer_advance = blk_size * blk_size;
+
+                        /* Global offset advance after each I/O operation */                            
+                        /* file_offset_advance = (off_t)(snbytes/blk_size*(blk_size*blk_size)); */
+                        file_offset_advance = (off_t)(snbytes*blk_size);
+                    } /* end else */
+                } /* end else */
+
+                /* Common code for file access */
+
+                /* Set the base of user's buffer */
+                buf_p = (unsigned char *)buffer;
+
+                /* Set the number of bytes to transfer this time */
+                nbytes_toxfer = buf_size*blk_size;
+
+                /* Loop over portions of the buffer to write */
+                while(nbytes_toxfer>0){
+                    /* only care if seek returns error */
+                    rc = POSIXSEEK(fd->posixfd, file_offset) < 0 ? -1 : 0;
+                    VRFY((rc==0), "POSIXSEEK");
+
+                    /* check if all bytes are written */
+                    rc = ((ssize_t)nbytes_xfer_advance ==
+                        POSIXWRITE(fd->posixfd, buf_p, nbytes_xfer_advance));
+                    VRFY((rc != 0), "POSIXWRITE");
+
+                    /* Advance location in buffer */
+                    buf_p+=nbytes_xfer_advance;
+
+                    /* Advance global offset in dataset */
+                    nbytes_xfer+=nbytes_xfer_advance;
+
+                    /* Decrement number of bytes left this time */
+                    nbytes_toxfer-=nbytes_xfer_advance;
+
+                    /* Partially advance file offset */
+                    file_offset+=file_offset_advance;
+                } /* end while */
+
+            } /* end else */
+
+            break;
+
+        case MPIO:
+            /* 1D dataspace */
+            if (!parms->dim2d){
+                /* Independent file access */
+                if(!parms->collective) {
+                    /* Contiguous pattern */
+                    if (!parms->interleaved){
+                        /* Compute offset in file */
+                        mpi_offset = mpi_file_offset +
+                            nbytes_xfer;
+
+                        /* Perform independent write */
+                        mrc = MPI_File_write_at(fd->mpifd, mpi_offset, buffer,
+                            (int)(buf_size/blk_size), mpi_blk_type,
+                            &mpi_status);
+                        VRFY((mrc==MPI_SUCCESS), "MPIO_WRITE");
+
+                        /* Advance global offset in dataset */
+                        nbytes_xfer+=buf_size;
+                    } /* end if */
+                    /* Interleaved access pattern */
+                    else {
+                        /* Set the base of user's buffer */
+                        buf_p=(unsigned char *)buffer;
+
+                        /* Set the number of bytes to transfer this time */
+                        nbytes_toxfer = buf_size;
+
+                        /* Loop over the buffers to write */
+                        while(nbytes_toxfer>0) {
+                            /* Skip offset over blocks of other processes */
+                            mpi_offset = mpi_file_offset +
+                            (nbytes_xfer*pio_mpi_nprocs_g);
+
+                            /* Perform independent write */
+                            mrc = MPI_File_write_at(fd->mpifd, mpi_offset, buf_p,
+                                (int)1, mpi_blk_type, &mpi_status);
+                            VRFY((mrc==MPI_SUCCESS), "MPIO_WRITE");
+
+                            /* Advance location in buffer */
+                            buf_p+=blk_size;
+
+                            /* Advance global offset in dataset */
+                            nbytes_xfer+=blk_size;
+
+                            /* Decrement number of bytes left this time */
+                            nbytes_toxfer-=blk_size;
+                        } /* end while */
+                    } /* end else */
+                } /* end if */
+                /* Collective file access */
+                else {
+                    /* Contiguous access pattern */
+                    if (!parms->interleaved){
+                        /* Compute offset in file */
+                        mpi_offset = mpi_file_offset +
+                            nbytes_xfer;
+
+                        /* Perform independent write */
+                        mrc = MPI_File_write_at_all(fd->mpifd, mpi_offset, buffer,
+                            (int)(buf_size/blk_size), mpi_blk_type, &mpi_status);
+                        VRFY((mrc==MPI_SUCCESS), "MPIO_WRITE");
+
+                        /* Advance global offset in dataset */
+                        nbytes_xfer+=buf_size;
+                    } /* end if */
+                    /* Interleaved access pattern */
+                    else {
+                        /* Compute offset in file */
+                        mpi_offset = mpi_file_offset +
+                            (nbytes_xfer*pio_mpi_nprocs_g);
+
+                        /* Set the file view */
+                        mrc = MPI_File_set_view(fd->mpifd, mpi_offset, mpi_blk_type,
+                            mpi_file_type, (char*)"native",  h5_io_info_g);
+                        VRFY((mrc==MPI_SUCCESS), "MPIO_VIEW");
+
+                        /* Perform write */
+                        mrc = MPI_File_write_at_all(fd->mpifd, 0, buffer,
+                            (int)(buf_size/blk_size), mpi_blk_type, &mpi_status);
+                        VRFY((mrc==MPI_SUCCESS), "MPIO_WRITE");
+
+                        /* Advance global offset in dataset */
+                        nbytes_xfer+=buf_size;
+                    } /* end else */
+                } /* end else */
+            } /* end if */
+            /* 2D dataspace */
+            else {
+                /* Contiguous storage */
+                if (!parms->h5_use_chunks) {
+                    /* Contiguous access pattern */
+                    if (!parms->interleaved) {
+                        /* Compute offset in file */
+                        mpi_offset=mpi_file_offset+((nbytes_xfer/blk_size)/snbytes)*
+                            (blk_size*snbytes)+((nbytes_xfer/blk_size)%snbytes);
+
+                        /* Number of bytes to be transferred per I/O operation */
+                        nbytes_xfer_advance = buf_size;
+
+                        /* Global offset advance after each I/O operation */                            
+                        mpi_offset_advance = snbytes;
+
+                        /* MPI type to be used for collective access */
+                        mpi_collective_type = mpi_cont_type;
+                    } /* end if */
+                    /* Interleaved access pattern */
+                    else {
+                        /* Compute offset in file */
+                        mpi_offset=mpi_file_offset+(((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)/snbytes)*
+                            (buf_size*snbytes)+((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)%snbytes;
+
+                        /* Number of bytes to be transferred per I/O operation */
+                        nbytes_xfer_advance = blk_size;
+
+                        /* Global offset advance after each I/O operation */                            
+                        mpi_offset_advance = snbytes;
+
+                        /* MPI type to be used for collective access */
+                        mpi_collective_type = mpi_inter_type;
+                    } /* end else */
+                } /* end if */
+                /* Chunked storage */
+                else {
+                    /*Contiguous access pattern */
+                    if (!parms->interleaved) {
+                        /* Compute offset in file */
+                        mpi_offset=mpi_file_offset+nbytes_xfer;
+
+                        /* Number of bytes to be transferred per I/O operation */
+                        nbytes_xfer_advance = blk_size * buf_size;
+
+                        /* Global offset advance after each I/O operation */                            
+                        mpi_offset_advance = 0;
+
+                        /* MPI type to be used for collective access */
+                        mpi_collective_type = mpi_full_buffer;
+                    } /* end if */
+                    /*Interleaved access pattern */
+                    else {
+                        /* Compute offset in file */
+                        /* Before simplification */
+                        /* mpi_offset=mpi_file_offset+(nbytes_xfer/(buf_size/blk_size)
+                            *pio_mpi_nprocs_g)/(snbytes/blk_size*(blk_size*blk_size))*
+                            (buf_size/blk_size*snbytes/blk_size*(blk_size*blk_size))+
+                            ((nbytes_xfer/(buf_size/blk_size))*pio_mpi_nprocs_g)%(snbytes
+                            /blk_size*(blk_size*blk_size)); */
+                        mpi_offset=mpi_file_offset+((nbytes_xfer/(buf_size/blk_size)
+                            *pio_mpi_nprocs_g)/(snbytes*blk_size))*(buf_size*snbytes)
+                            +((nbytes_xfer/(buf_size/blk_size))*pio_mpi_nprocs_g)%(snbytes*blk_size);
+
+                        /* Number of bytes to be transferred per I/O operation */
+                        nbytes_xfer_advance = blk_size * blk_size;
+
+                        /* Global offset advance after each I/O operation */                            
+                        /* mpi_offset_advance = (MPI_Offset)(snbytes/blk_size*(blk_size*blk_size)); */
+                        mpi_offset_advance = (MPI_Offset)(snbytes*blk_size);
+
+                        /* MPI type to be used for collective access */
+                        mpi_collective_type = mpi_chunk_inter_type;
+                    } /* end else */
+                } /* end else */
+
+                /* Common code for independent file access */
+                if (!parms->collective) {
+                    /* Set the base of user's buffer */
+                    buf_p = (unsigned char *)buffer;
+
+                    /* Set the number of bytes to transfer this time */
+                    nbytes_toxfer = buf_size * blk_size;
+
+                    /* Loop over portions of the buffer to write */
+                    while(nbytes_toxfer>0){
+                        /* Perform independent write */
+                        mrc = MPI_File_write_at(fd->mpifd, mpi_offset, buf_p,
+                            (int)nbytes_xfer_advance, MPI_BYTE, &mpi_status);
+                        VRFY((mrc==MPI_SUCCESS), "MPIO_WRITE");
+
+                        /* Advance location in buffer */
+                        buf_p+=nbytes_xfer_advance;
+
+                        /* Advance global offset in dataset */
+                        nbytes_xfer+=nbytes_xfer_advance;
+
+                        /* Decrement number of bytes left this time */
+                        nbytes_toxfer-=nbytes_xfer_advance;
+
+                        /* Partially advance global offset in dataset */
+                        mpi_offset+=mpi_offset_advance;
+                    } /* end while */
+                } /* end if */
+
+                /* Common code for collective file access */
+                else {
+                    /* Set the file view */
+                    mrc = MPI_File_set_view(fd->mpifd, mpi_offset, MPI_BYTE,
+                        mpi_collective_type, (char *)"native", h5_io_info_g);
+                    VRFY((mrc==MPI_SUCCESS), "MPIO_VIEW");
+
+                    /* Perform write */
+                    MPI_File_write_at_all(fd->mpifd, 0, buffer,(int)(buf_size*blk_size),
+                        MPI_BYTE, &mpi_status);
+                    VRFY((mrc==MPI_SUCCESS), "MPIO_WRITE");
+
+                    /* Advance global offset in dataset */
+                    nbytes_xfer+=buf_size*blk_size;
+                } /* end else */
+
+            } /* end else */
+
+            break;
+
+        case PHDF5:
+            /* 1D dataspace */
+            if (!parms->dim2d){
+            /* Set up the file dset space id to move the selection to process */
+            if (!parms->interleaved){
+                /* Contiguous pattern */
+                h5offset[0] = nbytes_xfer;
+            } /* end if */
+            else {
+                /* Interleaved access pattern */
+                /* Skip offset over blocks of other processes */
+                h5offset[0] = (nbytes_xfer*pio_mpi_nprocs_g);
+            } /* end else */
+            hrc = H5Soffset_simple(h5dset_space_id, h5offset);
+            VRFY((hrc >= 0), "H5Soffset_simple");
+
+            /* Write the buffer out */
+            hrc = H5Dwrite(h5ds_id, ELMT_H5_TYPE, h5mem_space_id,
+                h5dset_space_id, h5dxpl, buffer);
+            VRFY((hrc >= 0), "H5Dwrite");
+
+            /* Increment number of bytes transferred */
+            nbytes_xfer += buf_size;
+            } /* end if */
+            /* 2D dataspace */
+            else {
+            /* Set up the file dset space id to move the selection to process */
+            if (!parms->interleaved){
+                /* Contiguous pattern */
+                h5offset[0] = (nbytes_xfer/(snbytes*blk_size))*blk_size;
+                h5offset[1] = (nbytes_xfer%(snbytes*blk_size))/blk_size;
+
+            } /* end if */
+            else {
+                /* Interleaved access pattern */
+                /* Skip offset over blocks of other processes */
+                h5offset[0] = ((nbytes_xfer*pio_mpi_nprocs_g)/(snbytes*buf_size))*buf_size;
+                h5offset[1] = ((nbytes_xfer*pio_mpi_nprocs_g)%(snbytes*buf_size))/buf_size;
+
+            } /* end else */
+            hrc = H5Soffset_simple(h5dset_space_id, h5offset);
+            VRFY((hrc >= 0), "H5Soffset_simple");
+
+            /* Write the buffer out */
+            hrc = H5Dwrite(h5ds_id, ELMT_H5_TYPE, h5mem_space_id,
+                h5dset_space_id, h5dxpl, buffer);
+            VRFY((hrc >= 0), "H5Dwrite");
+
+            /* Increment number of bytes transferred */
+            nbytes_xfer += buf_size*blk_size;
+
+            } /* end else */
+
+            break;
+        } /* switch (parms->io_type) */
+    } /* end while */
+
+    /* Stop "raw data" write timer */
+    set_time(res->timers, HDF5_RAW_WRITE_FIXED_DIMS, STOP);
+
+    /* Calculate write time */
+
+    /* Close dataset. Only HDF5 needs to do an explicit close. */
+    if (parms->io_type == PHDF5) {
+        hrc = H5Dclose(h5ds_id);
+
+        if (hrc < 0) {
+        fprintf(stderr, "HDF5 Dataset Close failed\n");
+        GOTOERROR(FAIL);
+        }
+
+        h5ds_id = -1;
+    } /* end if */
     } /* end for */
 
 done:
     /* release MPI-I/O objects */
     if (parms->io_type == MPIO) {
-	/* 1D dataspace */
-	if (parms->dim2d==0){
-	    /* Free file type */
-	    mrc = MPI_Type_free( &mpi_file_type );
-	    VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
-
-	    /* Free buffer type */
-	    mrc = MPI_Type_free( &mpi_blk_type );
-	    VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
-	} /* end if */
-	/* 2D dataspace */
-	else {
-	    /* Free file type */
-	    mrc = MPI_Type_free( &mpi_cont_type );
-	    VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
-
-	    /* Free partial buffer type */
-	    mrc = MPI_Type_free( &contig_cont );
-	    VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
-
-	    /* Free file type */
-	    mrc = MPI_Type_free( &mpi_inter_type );
-	    VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
-
-	    /* Free partial buffer type */
-	    mrc = MPI_Type_free( &contig_inter );
-	    VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
-	} /* end else */
+        /* 1D dataspace */
+        if (!parms->dim2d){
+            /* Free file type */
+            mrc = MPI_Type_free( &mpi_file_type );
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+
+            /* Free buffer type */
+            mrc = MPI_Type_free( &mpi_blk_type );
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+        } /* end if */
+        /* 2D dataspace */
+        else {
+            /* Free partial buffer type for contiguous access */
+            mrc = MPI_Type_free( &mpi_partial_buffer_cont );
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+
+            /* Free contiguous file type */
+            mrc = MPI_Type_free( &mpi_cont_type );
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+
+            /* Free partial buffer type for interleaved access */
+            mrc = MPI_Type_free( &mpi_partial_buffer_inter );
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+
+            /* Free interleaved file type */
+            mrc = MPI_Type_free( &mpi_inter_type );
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+
+            /* Free full buffer type */
+            mrc = MPI_Type_free(&mpi_full_buffer);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+
+            /* Free full chunk type */
+            mrc = MPI_Type_free(&mpi_full_chunk);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+        
+            /* Free chunk interleaved file type */
+            mrc = MPI_Type_free(&mpi_chunk_inter_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+        } /* end else */
     } /* end if */
 
     /* release HDF5 objects */
     if (h5dset_space_id != -1) {
-	hrc = H5Sclose(h5dset_space_id);
-	if (hrc < 0){
-	    fprintf(stderr, "HDF5 Dataset Space Close failed\n");
-	    ret_code = FAIL;
-	} else {
-	    h5dset_space_id = -1;
-	}
+    hrc = H5Sclose(h5dset_space_id);
+    if (hrc < 0){
+        fprintf(stderr, "HDF5 Dataset Space Close failed\n");
+        ret_code = FAIL;
+    } else {
+        h5dset_space_id = -1;
+    }
     }
 
     if (h5mem_space_id != -1) {
-	hrc = H5Sclose(h5mem_space_id);
-	if (hrc < 0) {
-	    fprintf(stderr, "HDF5 Memory Space Close failed\n");
-	    ret_code = FAIL;
-	} else {
-	    h5mem_space_id = -1;
-	}
+    hrc = H5Sclose(h5mem_space_id);
+    if (hrc < 0) {
+        fprintf(stderr, "HDF5 Memory Space Close failed\n");
+        ret_code = FAIL;
+    } else {
+        h5mem_space_id = -1;
+    }
     }
 
     if (h5dxpl != -1) {
-	hrc = H5Pclose(h5dxpl);
-	if (hrc < 0) {
-	    fprintf(stderr, "HDF5 Dataset Transfer Property List Close failed\n");
-	    ret_code = FAIL;
-	} else {
-	    h5dxpl = -1;
-	}
+    hrc = H5Pclose(h5dxpl);
+    if (hrc < 0) {
+        fprintf(stderr, "HDF5 Dataset Transfer Property List Close failed\n");
+        ret_code = FAIL;
+    } else {
+        h5dxpl = -1;
+    }
     }
 
     return ret_code;
 }
 
 /*
- * Function:	    do_read
- * Purpose:			read the required amount of data from the file.
- * Return:			SUCCESS or FAIL
- * Programmer:		Albert Cheng 2001/12/13
+ * Function:        do_read
+ * Purpose:         read the required amount of data from the file.
+ * Return:          SUCCESS or FAIL
+ * Programmer:      Albert Cheng 2001/12/13
  * Modifications:
  *  Added 2D testing (Christian Chilan, 10. August 2005)
  */
     static herr_t
 do_read(results *res, file_descr *fd, parameters *parms, long ndsets,
-	off_t nbytes, size_t buf_size, void *buffer /*out*/)
+    off_t nbytes, size_t buf_size, void *buffer /*out*/)
 {
     int         ret_code = SUCCESS;
     int         rc;             /*routine return code                   */
     long        ndset;
     size_t      blk_size;       /* The block size to subdivide the xfer buffer into */
-    size_t		bsize;
+    size_t      bsize;          /* Size of the actual buffer */
     off_t       nbytes_xfer;    /* Total number of bytes transferred so far */
+    size_t      nbytes_xfer_advance; /* Number of bytes transferred in a single I/O operation */
     size_t      nbytes_toxfer;  /* Number of bytes to transfer a particular time */
     char        dname[64];
     off_t       dset_offset=0;  /*dataset offset in a file              */
     off_t       bytes_begin[2];    /*first elmt this process transfer      */
     off_t       bytes_count;    /*number of elmts this process transfer */
-    off_t		snbytes=0;		/*size of a side of the dataset square */
+    off_t       snbytes=0;      /*size of a side of the dataset square */
     unsigned char *buf_p;       /* Current buffer pointer               */
 
     /* POSIX variables */
     off_t       file_offset;    /* File offset of the next transfer    */
+    off_t       file_offset_advance; /* File offset advance after each I/O operation */
     off_t       posix_file_offset;    /* Base file offset of the next transfer      */
 
     /* MPI variables */
     MPI_Offset  mpi_file_offset;/* Base file offset of the next transfer*/
-    MPI_Offset	mpi_offset;     /* Offset in MPI file                   */
+    MPI_Offset  mpi_offset;     /* Offset in MPI file                   */
+    MPI_Offset  mpi_offset_advance; /* Offset advance after each I/O operation */
     MPI_Datatype mpi_file_type; /* MPI derived type for 1D file            */
     MPI_Datatype mpi_blk_type;  /* MPI derived type for 1D buffer          */
     MPI_Datatype mpi_cont_type; /* MPI derived type for 2D contiguous file */
-    MPI_Datatype contig_cont;	/* MPI derived type for 2D contiguous buffer */
-    MPI_Datatype mpi_inter_type;/* MPI derived type for 2D interleaved file  */
-    MPI_Datatype contig_inter;  /* MPI derived type for 2D interleaved buffer*/
-    MPI_Status	mpi_status;
+    MPI_Datatype mpi_partial_buffer_cont;       /* MPI derived type for partial 2D contiguous buffer */
+    MPI_Datatype mpi_inter_type;    /* MPI derived type for 2D interleaved file  */
+    MPI_Datatype mpi_partial_buffer_inter;      /* MPI derived type for partial 2D interleaved buffer */
+    MPI_Datatype mpi_full_buffer;       /* MPI derived type for 2D full buffer */
+    MPI_Datatype mpi_full_chunk;        /* MPI derived type for 2D full chunk */
+    MPI_Datatype mpi_chunk_inter_type;  /* MPI derived type for 2D chunk interleaved file */
+    MPI_Datatype mpi_collective_type;   /* Generic MPI derived type for 2D collective access */
+    MPI_Status  mpi_status;
     int         mrc;            /* MPI return code                      */
 
     /* HDF5 variables */
@@ -1413,11 +1534,11 @@ do_read(results *res, file_descr *fd, parameters *parms, long ndsets,
     hid_t       h5dset_space_id = -1;   /*dataset space ID              */
     hid_t       h5mem_space_id = -1;    /*memory dataspace ID           */
     hid_t       h5ds_id = -1;           /*dataset handle                */
-    hsize_t	h5block[2];		/*dataspace selection           */
-    hsize_t	h5stride[2];
-    hsize_t	h5count[2];
-    hsize_t	h5start[2];
-    hssize_t	h5offset[2];            /* Selection offset within dataspace */
+    hsize_t h5block[2];     /*dataspace selection           */
+    hsize_t h5stride[2];
+    hsize_t h5count[2];
+    hsize_t h5start[2];
+    hssize_t    h5offset[2];            /* Selection offset within dataspace */
     hid_t       h5dxpl = -1;            /* Dataset transfer property list */
 
     /* Get the parameters from the parameter block */
@@ -1434,38 +1555,41 @@ do_read(results *res, file_descr *fd, parameters *parms, long ndsets,
      */
 
     /* 1D dataspace */
-    if (parms->dim2d==0){
-	bsize = buf_size;
-	if (parms->interleaved==0) {
-	    /* Contiguous Pattern: */
-	    bytes_begin[0] = (off_t)(((double)nbytes*pio_mpi_rank_g)/pio_mpi_nprocs_g);
-	} /* end if */
-	else {
-	    /* Interleaved Pattern: */
-	    bytes_begin[0] = (off_t)(blk_size*pio_mpi_rank_g);
-	} /* end else */
+    if (!parms->dim2d){
+        bsize = buf_size;
+        /* Contiguous Pattern: */
+        if (!parms->interleaved) {
+             bytes_begin[0] = (off_t)(((double)nbytes*pio_mpi_rank_g)/pio_mpi_nprocs_g);
+        } /* end if */
+        /* Interleaved Pattern: */
+        else {
+            bytes_begin[0] = (off_t)(blk_size*pio_mpi_rank_g);
+        } /* end else */
     }/* end if */
     /* 2D dataspace */
     else {
-	snbytes = (off_t)sqrt(nbytes);
-	bsize = buf_size * blk_size;
-	/* nbytes is always the number of bytes per dataset (1D or 2D). If the
-	   dataspace is 2D, snbytes is the size of a side of the 'dataset square'.
-	 */
-	if (parms->interleaved==0) {
-	    /* Contiguous Pattern: */
-	    bytes_begin[0] = (off_t)((double)snbytes*pio_mpi_rank_g / pio_mpi_nprocs_g);
-	    bytes_begin[1] = 0;
-	} /* end if */
-	else {
-	    /* Interleaved Pattern: */
-	    bytes_begin[0] = 0;
-	    bytes_begin[1] = (off_t)(blk_size*pio_mpi_rank_g);
-	} /* end else */
-    }
-
-    /* end else */
-
+        /* nbytes is always the number of bytes per dataset (1D or 2D). If the
+           dataspace is 2D, snbytes is the size of a side of the 'dataset square'.
+         */
+        snbytes = (off_t)sqrt(nbytes);
+
+        bsize = buf_size * blk_size;
+
+        /* Contiguous Pattern: */
+        if (!parms->interleaved) {
+            bytes_begin[0] = (off_t)((double)snbytes*pio_mpi_rank_g / pio_mpi_nprocs_g);
+            bytes_begin[1] = 0;
+        } /* end if */
+        /* Interleaved Pattern: */
+        else {
+            bytes_begin[0] = 0;
+
+            if (!parms->h5_use_chunks || parms->io_type==PHDF5) 
+                bytes_begin[1] = (off_t)(blk_size*pio_mpi_rank_g);
+            else
+                bytes_begin[1] = (off_t)(blk_size*blk_size*pio_mpi_rank_g);
+        } /* end else */
+    } /* end else */
 
     /* Calculate the total number of bytes (bytes_count) to be
      * transferred by this process. It may be different for different
@@ -1478,737 +1602,826 @@ do_read(results *res, file_descr *fd, parameters *parms, long ndsets,
      * (This is tricky, don't mess with the formula, rounding errors
      * can easily get introduced) */
     bytes_count = (off_t)(((double)nbytes*(pio_mpi_rank_g+1)) / pio_mpi_nprocs_g)
-	- (off_t)(((double)nbytes*pio_mpi_rank_g) / pio_mpi_nprocs_g);
+    - (off_t)(((double)nbytes*pio_mpi_rank_g) / pio_mpi_nprocs_g);
 
     /* debug */
     if (pio_debug_level >= 4) {
-	HDprint_rank(output);
-	HDfprintf(output, "Debug(do_read): "
-		"buf_size=%Hd, bytes_begin=%Hd, bytes_count=%Hd\n",
-		(long_long)buf_size, (long_long)bytes_begin,
-		(long_long)bytes_count);
+    HDprint_rank(output);
+    HDfprintf(output, "Debug(do_read): "
+        "buf_size=%Hd, bytes_begin=%Hd, bytes_count=%Hd\n",
+        (long_long)buf_size, (long_long)bytes_begin,
+        (long_long)bytes_count);
     }
 
     /* I/O Access specific setup */
     switch (parms->io_type) {
-	case POSIXIO:
-	    /* No extra setup */
-	    break;
-
-	case MPIO: /* MPI-I/O setup */
-	    /* 1D dataspace */
-	    if (parms->dim2d==0){
-		/* Build block's derived type */
-		mrc = MPI_Type_contiguous((int)blk_size,
-			MPI_BYTE, &mpi_blk_type);
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
-
-		/* Build file's derived type */
-		mrc = MPI_Type_vector((int)(buf_size/blk_size), (int)1,
-			(int)pio_mpi_nprocs_g, mpi_blk_type, &mpi_file_type);
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
-
-		/* Commit file type */
-		mrc = MPI_Type_commit( &mpi_file_type );
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
-
-		/* Commit buffer type */
-		mrc = MPI_Type_commit( &mpi_blk_type );
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
-	    } /* end if */
-	    /* 2D dataspace */
-	    else {
-		/* Build partial buffer derived type for contiguous access */
-		mrc = MPI_Type_contiguous((int)buf_size, MPI_BYTE,
-			&contig_cont);
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
-
-		/* Build contiguous file's derived type */
-		mrc = MPI_Type_vector((int)blk_size, (int)1, (int)(snbytes/buf_size),
-			contig_cont, &mpi_cont_type);
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
-
-		/* Commit contiguous file type */
-		mrc = MPI_Type_commit(&mpi_cont_type);
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
-
-		/* Build partial buffer derived type for interleaved access */
-		mrc = MPI_Type_contiguous((int)blk_size, MPI_BYTE,
-			&contig_inter);
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
-
-		/* Build interleaved file's derived type */
-		mrc = MPI_Type_vector((int)buf_size, (int)1, (int)(snbytes/blk_size),
-			contig_inter, &mpi_inter_type);
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
-
-		/* Commit interleaved buffer type */
-		mrc = MPI_Type_commit(&mpi_inter_type);
-		VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
-	    } /* end else */
-	    break;
-
-	case PHDF5: /* HDF5 setup */
-	    /* 1D dataspace */
-	    if (parms->dim2d==0){
-		if(nbytes>0) {
-		    /* define a contiguous dataset of nbytes native bytes */
-		    h5dims[0] = nbytes;
-		    h5dset_space_id = H5Screate_simple(1, h5dims, NULL);
-		    VRFY((h5dset_space_id >= 0), "H5Screate_simple");
-
-		    /* Set up the file dset space id to select the pattern to access */
-		    if (parms->interleaved==0){
-			/* Contiguous pattern */
-			h5start[0] = bytes_begin[0];
-			h5stride[0] = h5block[0] = blk_size;
-			h5count[0] = buf_size/blk_size;
-		    } /* end if */
-		    else {
-			/* Interleaved access pattern */
-			/* Skip offset over blocks of other processes */
-			h5start[0] = bytes_begin[0];
-			h5stride[0] = blk_size*pio_mpi_nprocs_g;
-			h5block[0] = blk_size;
-			h5count[0] = buf_size/blk_size;
-		    } /* end else */
-		    hrc = H5Sselect_hyperslab(h5dset_space_id, H5S_SELECT_SET,
-			    h5start, h5stride, h5count, h5block);
-		    VRFY((hrc >= 0), "H5Sselect_hyperslab");
-		} /* end if */
-		else {
-		    h5dset_space_id = H5Screate(H5S_SCALAR);
-		    VRFY((h5dset_space_id >= 0), "H5Screate");
-		} /* end else */
-
-		/* Create the memory dataspace that corresponds to the xfer buffer */
-		if(buf_size>0) {
-		    h5dims[0] = buf_size;
-		    h5mem_space_id = H5Screate_simple(1, h5dims, NULL);
-		    VRFY((h5mem_space_id >= 0), "H5Screate_simple");
-		} /* end if */
-		else {
-		    h5mem_space_id = H5Screate(H5S_SCALAR);
-		    VRFY((h5mem_space_id >= 0), "H5Screate");
-		} /* end else */
-	    } /* end if */
-	    /* 2D dataspace */
-	    else {
-		if(nbytes>0) {
-		    /* define a contiguous dataset of nbytes native bytes */
-		    h5dims[0] = snbytes;
-		    h5dims[1] = snbytes;
-		    h5dset_space_id = H5Screate_simple(2, h5dims, NULL);
-		    VRFY((h5dset_space_id >= 0), "H5Screate_simple");
-
-		    /* Set up the file dset space id to select the pattern to access */
-		    if (parms->interleaved==0){
-			/* Contiguous pattern */
-			h5start[0] = bytes_begin[0];
-			h5start[1] = bytes_begin[1];
-			h5stride[0] = 1;
-			h5stride[1] = h5block[0] = h5block[1] = blk_size;
-			h5count[0] = 1;
-			h5count[1] = buf_size/blk_size;
-		    } /* end if */
-		    else {
-			/* Interleaved access pattern */
-			/* Skip offset over blocks of other processes */
-			h5start[0] = bytes_begin[0];
-			h5start[1] = bytes_begin[1];
-			h5stride[0] = blk_size;
-			h5stride[1] = blk_size*pio_mpi_nprocs_g;
-			h5block[0] = h5block[1] = blk_size;
-			h5count[0] = buf_size/blk_size;
-			h5count[1] = 1;
-		    } /* end else */
-		    hrc = H5Sselect_hyperslab(h5dset_space_id, H5S_SELECT_SET,
-			    h5start, h5stride, h5count, h5block);
-		    VRFY((hrc >= 0), "H5Sselect_hyperslab");
-		} /* end if */
-		else {
-		    h5dset_space_id = H5Screate(H5S_SCALAR);
-		    VRFY((h5dset_space_id >= 0), "H5Screate");
-		} /* end else */
-
-		/* Create the memory dataspace that corresponds to the xfer buffer */
-		if(buf_size>0) {
-		    if (parms->interleaved==0){
-			h5dims[0] = blk_size;
-			h5dims[1] = buf_size;
-		    }else{
-			h5dims[0] = buf_size;
-			h5dims[1] = blk_size;
-		    }
-		    h5mem_space_id = H5Screate_simple(2, h5dims, NULL);
-		    VRFY((h5mem_space_id >= 0), "H5Screate_simple");
-		} /* end if */
-		else {
-		    h5mem_space_id = H5Screate(H5S_SCALAR);
-		    VRFY((h5mem_space_id >= 0), "H5Screate");
-		} /* end else */
-	    } /* end else */
-
-	    /* Create the dataset transfer property list */
-	    h5dxpl = H5Pcreate(H5P_DATASET_XFER);
-	    if (h5dxpl < 0) {
-		fprintf(stderr, "HDF5 Property List Create failed\n");
-		GOTOERROR(FAIL);
-	    }
-
-	    /* Change to collective I/O, if asked */
-	    if(parms->collective) {
-		hrc = H5Pset_dxpl_mpio(h5dxpl, H5FD_MPIO_COLLECTIVE);
-		if (hrc < 0) {
-		    fprintf(stderr, "HDF5 Property List Set failed\n");
-		    GOTOERROR(FAIL);
-		} /* end if */
-	    } /* end if */
-	    break;
+    case POSIXIO:
+        /* No extra setup */
+        break;
+
+    case MPIO: /* MPI-I/O setup */
+        /* 1D dataspace */
+        if (!parms->dim2d){
+            /* Build block's derived type */
+            mrc = MPI_Type_contiguous((int)blk_size,
+                MPI_BYTE, &mpi_blk_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Build file's derived type */
+            mrc = MPI_Type_vector((int)(buf_size/blk_size), (int)1,
+                (int)pio_mpi_nprocs_g, mpi_blk_type, &mpi_file_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Commit file type */
+            mrc = MPI_Type_commit( &mpi_file_type );
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+
+            /* Commit buffer type */
+            mrc = MPI_Type_commit( &mpi_blk_type );
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+        } /* end if */
+        /* 2D dataspace */
+        else {
+            /* Build partial buffer derived type for contiguous access */
+            mrc = MPI_Type_contiguous((int)buf_size, MPI_BYTE,
+                &mpi_partial_buffer_cont);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Commit partial buffer derived type */
+            mrc = MPI_Type_commit(&mpi_partial_buffer_cont);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+            
+            /* Build contiguous file's derived type */
+            mrc = MPI_Type_vector((int)blk_size, (int)1, (int)(snbytes/buf_size),
+                mpi_partial_buffer_cont, &mpi_cont_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Commit contiguous file type */
+            mrc = MPI_Type_commit(&mpi_cont_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+
+            /* Build partial buffer derived type for interleaved access */
+            mrc = MPI_Type_contiguous((int)blk_size, MPI_BYTE,
+                &mpi_partial_buffer_inter);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Commit partial buffer derived type */
+            mrc = MPI_Type_commit(&mpi_partial_buffer_inter);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+
+            /* Build interleaved file's derived type */
+            mrc = MPI_Type_vector((int)buf_size, (int)1, (int)(snbytes/blk_size),
+                mpi_partial_buffer_inter, &mpi_inter_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Commit interleaved file type */
+            mrc = MPI_Type_commit(&mpi_inter_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+
+            /* Build full buffer derived type */
+            mrc = MPI_Type_contiguous((int)(blk_size*buf_size), MPI_BYTE,
+                &mpi_full_buffer);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Commit full buffer derived type */
+            mrc = MPI_Type_commit(&mpi_full_buffer);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+
+            /* Build full chunk derived type */               
+            mrc = MPI_Type_contiguous((int)(blk_size*blk_size), MPI_BYTE,
+                &mpi_full_chunk);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Commit full chunk derived type */
+            mrc = MPI_Type_commit(&mpi_full_chunk);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+
+            /* Build chunk interleaved file's derived type */             
+            mrc = MPI_Type_vector((int)(buf_size/blk_size), (int)1, (int)(snbytes/blk_size),
+                mpi_full_chunk, &mpi_chunk_inter_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_CREATE");
+
+            /* Commit chunk interleaved file type */
+            mrc = MPI_Type_commit(&mpi_chunk_inter_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_COMMIT");
+        } /* end else */
+        break;
+
+    case PHDF5: /* HDF5 setup */
+        /* 1D dataspace */
+        if (!parms->dim2d){
+        if(nbytes>0) {
+            /* define a contiguous dataset of nbytes native bytes */
+            h5dims[0] = nbytes;
+            h5dset_space_id = H5Screate_simple(1, h5dims, NULL);
+            VRFY((h5dset_space_id >= 0), "H5Screate_simple");
+
+            /* Set up the file dset space id to select the pattern to access */
+            if (!parms->interleaved){
+            /* Contiguous pattern */
+            h5start[0] = bytes_begin[0];
+            h5stride[0] = h5block[0] = blk_size;
+            h5count[0] = buf_size/blk_size;
+            } /* end if */
+            else {
+            /* Interleaved access pattern */
+            /* Skip offset over blocks of other processes */
+            h5start[0] = bytes_begin[0];
+            h5stride[0] = blk_size*pio_mpi_nprocs_g;
+            h5block[0] = blk_size;
+            h5count[0] = buf_size/blk_size;
+            } /* end else */
+            hrc = H5Sselect_hyperslab(h5dset_space_id, H5S_SELECT_SET,
+                h5start, h5stride, h5count, h5block);
+            VRFY((hrc >= 0), "H5Sselect_hyperslab");
+        } /* end if */
+        else {
+            h5dset_space_id = H5Screate(H5S_SCALAR);
+            VRFY((h5dset_space_id >= 0), "H5Screate");
+        } /* end else */
+
+        /* Create the memory dataspace that corresponds to the xfer buffer */
+        if(buf_size>0) {
+            h5dims[0] = buf_size;
+            h5mem_space_id = H5Screate_simple(1, h5dims, NULL);
+            VRFY((h5mem_space_id >= 0), "H5Screate_simple");
+        } /* end if */
+        else {
+            h5mem_space_id = H5Screate(H5S_SCALAR);
+            VRFY((h5mem_space_id >= 0), "H5Screate");
+        } /* end else */
+        } /* end if */
+        /* 2D dataspace */
+        else {
+        if(nbytes>0) {
+            /* define a contiguous dataset of nbytes native bytes */
+            h5dims[0] = snbytes;
+            h5dims[1] = snbytes;
+            h5dset_space_id = H5Screate_simple(2, h5dims, NULL);
+            VRFY((h5dset_space_id >= 0), "H5Screate_simple");
+
+            /* Set up the file dset space id to select the pattern to access */
+            if (!parms->interleaved){
+            /* Contiguous pattern */
+            h5start[0] = bytes_begin[0];
+            h5start[1] = bytes_begin[1];
+            h5stride[0] = 1;
+            h5stride[1] = h5block[0] = h5block[1] = blk_size;
+            h5count[0] = 1;
+            h5count[1] = buf_size/blk_size;
+            } /* end if */
+            else {
+            /* Interleaved access pattern */
+            /* Skip offset over blocks of other processes */
+            h5start[0] = bytes_begin[0];
+            h5start[1] = bytes_begin[1];
+            h5stride[0] = blk_size;
+            h5stride[1] = blk_size*pio_mpi_nprocs_g;
+            h5block[0] = h5block[1] = blk_size;
+            h5count[0] = buf_size/blk_size;
+            h5count[1] = 1;
+            } /* end else */
+            hrc = H5Sselect_hyperslab(h5dset_space_id, H5S_SELECT_SET,
+                h5start, h5stride, h5count, h5block);
+            VRFY((hrc >= 0), "H5Sselect_hyperslab");
+        } /* end if */
+        else {
+            h5dset_space_id = H5Screate(H5S_SCALAR);
+            VRFY((h5dset_space_id >= 0), "H5Screate");
+        } /* end else */
+
+        /* Create the memory dataspace that corresponds to the xfer buffer */
+        if(buf_size>0) {
+            if (!parms->interleaved){
+            h5dims[0] = blk_size;
+            h5dims[1] = buf_size;
+            }else{
+            h5dims[0] = buf_size;
+            h5dims[1] = blk_size;
+            }
+            h5mem_space_id = H5Screate_simple(2, h5dims, NULL);
+            VRFY((h5mem_space_id >= 0), "H5Screate_simple");
+        } /* end if */
+        else {
+            h5mem_space_id = H5Screate(H5S_SCALAR);
+            VRFY((h5mem_space_id >= 0), "H5Screate");
+        } /* end else */
+        } /* end else */
+
+        /* Create the dataset transfer property list */
+        h5dxpl = H5Pcreate(H5P_DATASET_XFER);
+        if (h5dxpl < 0) {
+        fprintf(stderr, "HDF5 Property List Create failed\n");
+        GOTOERROR(FAIL);
+        }
+
+        /* Change to collective I/O, if asked */
+        if(parms->collective) {
+        hrc = H5Pset_dxpl_mpio(h5dxpl, H5FD_MPIO_COLLECTIVE);
+        if (hrc < 0) {
+            fprintf(stderr, "HDF5 Property List Set failed\n");
+            GOTOERROR(FAIL);
+        } /* end if */
+        } /* end if */
+        break;
     } /* end switch */
 
-    for(ndset = 1; ndset <= ndsets; ++ndset) {
-
-	/* Calculate dataset offset within a file */
-
-	/* create dataset */
-	switch(parms->io_type) {
-	    case POSIXIO:
-	    case MPIO:
-		/* both posix and mpi io just need dataset offset in file*/
-		dset_offset = (ndset - 1) * nbytes;
-		break;
-
-	    case PHDF5:
-		sprintf(dname, "Dataset_%ld", ndset);
-		h5ds_id = H5Dopen2(fd->h5fd, dname, H5P_DEFAULT);
-		if(h5ds_id < 0) {
-		    fprintf(stderr, "HDF5 Dataset open failed\n");
-		    GOTOERROR(FAIL);
-		}
-		break;
-	}
-
-	/* The task is to transfer bytes_count bytes, starting at
-	 * bytes_begin position, using transfer buffer of buf_size bytes.
-	 * If interleaved, select buf_size at a time, in round robin
-	 * fashion, according to number of process. Otherwise, select
-	 * all bytes_count in contiguous.
-	 */
-	nbytes_xfer = 0 ;
-
-	/* 1D dataspace */
-	if (parms->dim2d==0){
-	    /* Set base file offset for all I/O patterns and POSIX access */
-	    posix_file_offset = dset_offset + bytes_begin[0];
-
-	    /* Set base file offset for all I/O patterns and MPI access */
-	    mpi_file_offset = (MPI_Offset)(dset_offset + bytes_begin[0]);
-	} /* end if */
-	else {
-	    /* Set base file offset for all I/O patterns and POSIX access */
-	    posix_file_offset=dset_offset + bytes_begin[0]*snbytes+
-		bytes_begin[1];
-
-	    /* Set base file offset for all I/O patterns and MPI access */
-	    mpi_file_offset=(MPI_Offset)(dset_offset + bytes_begin[0]*snbytes+
-		    bytes_begin[1]);
-	} /* end else */
-
-	/* Start "raw data" read timer */
-	set_time(res->timers, HDF5_RAW_READ_FIXED_DIMS, START);
-
-	while (nbytes_xfer < bytes_count){
-	    /* Read */
-	    /* Calculate offset of read within a dataset/file */
-	    switch (parms->io_type) {
-		case POSIXIO:
-		    /* 1D dataspace */
-		    if (parms->dim2d==0){
-			/* Contiguous pattern */
-			if (parms->interleaved==0) {
-			    /* Compute file offset */
-			    file_offset = posix_file_offset + (off_t)nbytes_xfer;
-
-			    /* only care if seek returns error */
-			    rc = POSIXSEEK(fd->posixfd, file_offset) < 0 ? -1 : 0;
-			    VRFY((rc==0), "POSIXSEEK");
-
-			    /* check if all bytes are read */
-			    rc = ((ssize_t)buf_size ==
-				    POSIXREAD(fd->posixfd, buffer, buf_size));
-			    VRFY((rc != 0), "POSIXREAD");
-
-			    /* Advance global offset in dataset */
-			    nbytes_xfer+=buf_size;
-			} /* end if */
-			/* Interleaved access pattern */
-			else {
-			    /* Set the base of user's buffer */
-			    buf_p=(unsigned char *)buffer;
-
-			    /* Set the number of bytes to transfer this time */
-			    nbytes_toxfer = buf_size;
-
-			    /* Loop over the buffers to read */
-			    while(nbytes_toxfer>0) {
-				/* Skip offset over blocks of other processes */
-				file_offset = posix_file_offset +
-				    (off_t)(nbytes_xfer*pio_mpi_nprocs_g);
-
-				/* only care if seek returns error */
-				rc = POSIXSEEK(fd->posixfd, file_offset) < 0 ? -1 : 0;
-				VRFY((rc==0), "POSIXSEEK");
-
-				/* check if all bytes are read */
-				rc = ((ssize_t)blk_size ==
-					POSIXREAD(fd->posixfd, buf_p, blk_size));
-				VRFY((rc != 0), "POSIXREAD");
-
-				/* Advance location in buffer */
-				buf_p+=blk_size;
-
-				/* Advance global offset in dataset */
-				nbytes_xfer+=blk_size;
-
-				/* Decrement number of bytes left this time */
-				nbytes_toxfer-=blk_size;
-			    } /* end while */
-			} /* end else */
-		    } /* end if */
-		    /* 2D dataspace */
-		    else {
-			/* Contiguous pattern */
-			if (parms->interleaved==0){
-			    /* Set the base of user's buffer */
-			    buf_p = (unsigned char *)buffer;
-
-			    /* Set the number of bytes to transfer this time */
-			    nbytes_toxfer = buf_size*blk_size;
-
-			    /* Compute file offset */
-			    file_offset=posix_file_offset+(off_t)(((nbytes_xfer/blk_size)/(snbytes))*
-				    (blk_size*snbytes)+((nbytes_xfer/blk_size)%(snbytes)));
-
-			    /* Loop over portions of the buffer to read */
-			    while(nbytes_toxfer>0){
-				/* only care if seek returns error */
-				rc = POSIXSEEK(fd->posixfd, file_offset) < 0 ? -1 : 0;
-				VRFY((rc==0), "POSIXSEEK");
-
-				/* check if all bytes are read */
-				rc = ((ssize_t)buf_size ==
-					POSIXREAD(fd->posixfd, buffer, buf_size));
-				VRFY((rc != 0), "POSIXREAD");
-
-				/* Advance location in buffer */
-				buf_p+=buf_size;
-
-				/* Advance global offset in dataset */
-				nbytes_xfer+=buf_size;
-
-				/* Decrement number of bytes left this time */
-				nbytes_toxfer-=buf_size;
-
-				/* Partially advance file offset */
-				file_offset+=(off_t)(snbytes);
-			    } /* end while */
-			} /* end if */
-			/* Interleaved access pattern */
-			else{
-			    /* Set the base of user's buffer */
-			    buf_p=(unsigned char *)buffer;
-
-			    /* Set the number of bytes to transfer this time */
-			    nbytes_toxfer=buf_size*blk_size;
-
-			    /* Compute file offset */
-			    file_offset=posix_file_offset+(off_t)(((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)/(snbytes)*
-				    (buf_size*snbytes)+((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)%(snbytes));
-
-			    /* Loop over portions of the buffer to read */
-			    while(nbytes_toxfer>0){
-				/* only care if seek returns error */
-				rc = POSIXSEEK(fd->posixfd, file_offset) < 0 ? -1 : 0;
-				VRFY((rc==0), "POSIXSEEK");
-
-				/* check if all bytes are read */
-				rc = ((ssize_t)blk_size ==
-					POSIXREAD(fd->posixfd, buffer, blk_size));
-				VRFY((rc != 0), "POSIXREAD");
-
-				/* Advance location in buffer */
-				buf_p+=blk_size;
-
-				/* Advance global offset in dataset */
-				nbytes_xfer+=blk_size;
-
-				/* Decrement number of bytes left this time */
-				nbytes_toxfer-=blk_size;
-
-				/* Partially advance file offset */
-				file_offset+=(off_t)(snbytes);
-			    } /* end while */
-			}/* end else */
-		    } /* end else */
-		    break;
-
-		case MPIO:
-		    /* 1D dataspace */
-		    if (parms->dim2d==0){
-			/* Independent file access */
-			if(parms->collective==0) {
-			    /* Contiguous pattern */
-			    if (parms->interleaved==0){
-				/* Compute offset in file */
-				mpi_offset = mpi_file_offset +
-				    nbytes_xfer;
-
-				/* Perform independent read */
-				mrc = MPI_File_read_at(fd->mpifd, mpi_offset, buffer,
-					(int)(buf_size/blk_size), mpi_blk_type,
-					&mpi_status);
-				VRFY((mrc==MPI_SUCCESS), "MPIO_READ");
-
-				/* Advance global offset in dataset */
-				nbytes_xfer+=buf_size;
-			    } /* end if */
-			    /* Interleaved access pattern */
-			    else {
-				/* Set the base of user's buffer */
-				buf_p=(unsigned char *)buffer;
-
-				/* Set the number of bytes to transfer this time */
-				nbytes_toxfer = buf_size;
-
-				/* Loop over the buffers to read */
-				while(nbytes_toxfer>0) {
-				    /* Skip offset over blocks of other processes */
-				    mpi_offset = mpi_file_offset +
-					(nbytes_xfer*pio_mpi_nprocs_g);
-
-				    /* Perform independent read */
-				    mrc = MPI_File_read_at(fd->mpifd, mpi_offset, buf_p,
-					    (int)1, mpi_blk_type, &mpi_status);
-				    VRFY((mrc==MPI_SUCCESS), "MPIO_READ");
-
-				    /* Advance location in buffer */
-				    buf_p+=blk_size;
-
-				    /* Advance global offset in dataset */
-				    nbytes_xfer+=blk_size;
-
-				    /* Decrement number of bytes left this time */
-				    nbytes_toxfer-=blk_size;
-				} /* end while */
-			    } /* end else */
-			} /* end if */
-			/* Collective file access */
-			else {
-			    /* Contiguous access pattern */
-			    if (parms->interleaved==0){
-				/* Compute offset in file */
-				mpi_offset = mpi_file_offset +
-				    nbytes_xfer;
-
-				/* Perform collective read */
-				mrc = MPI_File_read_at_all(fd->mpifd, mpi_offset, buffer,
-					(int)(buf_size/blk_size), mpi_blk_type, &mpi_status);
-				VRFY((mrc==MPI_SUCCESS), "MPIO_READ");
-
-				/* Advance global offset in dataset */
-				nbytes_xfer+=buf_size;
-			    } /* end if */
-			    /* Interleaved access pattern */
-			    else {
-				/* Compute offset in file */
-				mpi_offset = mpi_file_offset +
-				    (nbytes_xfer*pio_mpi_nprocs_g);
-
-				/* Set the file view */
-				mrc = MPI_File_set_view(fd->mpifd, mpi_offset, mpi_blk_type,
-					mpi_file_type, (char*)"native",  h5_io_info_g);
-				VRFY((mrc==MPI_SUCCESS), "MPIO_VIEW");
-
-				/* Perform collective read */
-				mrc = MPI_File_read_at_all(fd->mpifd, 0, buffer,
-					(int)(buf_size/blk_size), mpi_blk_type, &mpi_status);
-				VRFY((mrc==MPI_SUCCESS), "MPIO_READ");
-
-				/* Advance global offset in dataset */
-				nbytes_xfer+=buf_size;
-			    } /* end else */
-			} /* end else */
-		    } /* end if */
-		    /* 2D dataspace */
-		    else {
-			/* Independent file access */
-			if (parms->collective==0)
-			    /* Contiguous pattern */
-			    if (parms->interleaved==0){
-				/* Set the base of user's buffer */
-				buf_p = (unsigned char *)buffer;
-
-				/* Set the number of bytes to transfer this time */
-				nbytes_toxfer = buf_size*blk_size;
-
-				/* Compute offset in file */
-				mpi_offset=mpi_file_offset+((nbytes_xfer/blk_size)/(snbytes))*
-				    (blk_size*snbytes)+((nbytes_xfer/blk_size)%(snbytes));
-
-				/* Loop over portions of the buffer to read */
-				while(nbytes_toxfer>0){
-
-				    /* Perform independent write */
-				    mrc = MPI_File_read_at(fd->mpifd, mpi_offset, buf_p, (int)buf_size, MPI_BYTE, &mpi_status);
-				    VRFY((mrc==MPI_SUCCESS), "MPIO_READ");
-
-				    /* Advance location in buffer */
-				    buf_p+=buf_size;
-
-				    /* Advance global offset in dataset */
-				    nbytes_xfer+=buf_size;
-
-				    /* Decrement number of bytes left this time */
-				    nbytes_toxfer-=buf_size;
-
-				    /* Partially advance global offset in dataset */
-				    mpi_offset+=snbytes;
-				} /* end while */
-			    } /* end if */
-			/* Interleaved access pattern */
-			    else{
-				/* Set the base of user's buffer */
-				buf_p=(unsigned char *)buffer;
-
-				/* Set the number of bytes to transfer this time */
-				nbytes_toxfer=buf_size*blk_size;
-
-				/* Compute offset in file */
-				mpi_offset=mpi_file_offset+((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)/(snbytes)*
-				    (buf_size*snbytes)+((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)%(snbytes);
-
-				/* Loop over portions of the buffer to read */
-				while(nbytes_toxfer>0){
-				    /* Perform independent write */
-				    mrc = MPI_File_read_at(fd->mpifd, mpi_offset, buf_p, (int)blk_size, MPI_BYTE, &mpi_status);
-				    VRFY((mrc==MPI_SUCCESS), "MPIO_READ");
-
-				    /* Advance location in buffer */
-				    buf_p+=blk_size;
-
-				    /* Advance global offset in dataset */
-				    nbytes_xfer+=blk_size;
-
-				    /* Decrement number of bytes left this time */
-				    nbytes_toxfer-=blk_size;
-
-				    /* Partially advance global offset in dataset */
-				    mpi_offset+=snbytes;
-				} /* end while */
-			    } /* end else */
-			/* end if */
-			/* Collective file access */
-			else
-			    /* Contiguous access pattern */
-			    if (parms->interleaved==0){
-				/* Compute offset in file */
-				mpi_offset=mpi_file_offset+((nbytes_xfer/blk_size)/(snbytes))*
-				    (blk_size*snbytes)+((nbytes_xfer/blk_size)%(snbytes));
-
-				/* Set the file view */
-				mrc = MPI_File_set_view(fd->mpifd, mpi_offset, MPI_BYTE, mpi_cont_type, (char *)"native", h5_io_info_g);
-				VRFY((mrc==MPI_SUCCESS), "MPIO_VIEW");
-
-				/* Perform read */
-				mrc = MPI_File_read_at_all(fd->mpifd, 0, buffer,(int)(buf_size*blk_size),MPI_BYTE, &mpi_status);
-				VRFY((mrc==MPI_SUCCESS), "MPIO_READ");
-
-				nbytes_xfer+=buf_size*blk_size;
-			    } /* end if */
-			/* Interleaved access pattern */
-			    else{
-				/* Compute offset in file */
-				mpi_offset=mpi_file_offset+((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)/(snbytes)*
-				    (buf_size*snbytes)+((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)%(snbytes);
-
-				/* Set the file view */
-				mrc = MPI_File_set_view(fd->mpifd, mpi_offset, MPI_BYTE, mpi_inter_type, (char *)"native", h5_io_info_g);
-				VRFY((mrc==MPI_SUCCESS), "MPIO_VIEW");
-
-				/* Perform read */
-				mrc = MPI_File_read_at_all(fd->mpifd, 0, buffer, (int)(buf_size*blk_size), MPI_BYTE, &mpi_status);
-				VRFY((mrc==MPI_SUCCESS), "MPIO_READ");
-
-				nbytes_xfer+=buf_size*blk_size;
-			    } /* end else */
-			/* end else */
-		    } /* end else */
-		    break;
-
-		case PHDF5:
-		    /* 1D dataspace */
-		    if (parms->dim2d==0){
-			/* Set up the file dset space id to move the selection to process */
-			if (parms->interleaved==0){
-			    /* Contiguous pattern */
-			    h5offset[0] = nbytes_xfer;
-			} /* end if */
-			else {
-			    /* Interleaved access pattern */
-			    /* Skip offset over blocks of other processes */
-			    h5offset[0] = (nbytes_xfer*pio_mpi_nprocs_g);
-			} /* end else */
-			hrc = H5Soffset_simple(h5dset_space_id, h5offset);
-			VRFY((hrc >= 0), "H5Soffset_simple");
-
-			/* Read the buffer in */
-			hrc = H5Dread(h5ds_id, ELMT_H5_TYPE, h5mem_space_id,
-				h5dset_space_id, h5dxpl, buffer);
-			VRFY((hrc >= 0), "H5Dread");
-
-			/* Increment number of bytes transferred */
-			nbytes_xfer += buf_size;
-		    } /* end if */
-		    /* 2D dataspace */
-		    else {
-			/* Set up the file dset space id to move the selection to process */
-			if (parms->interleaved==0){
-			    /* Contiguous pattern */
-			    h5offset[0] = (nbytes_xfer/(snbytes*blk_size))*blk_size;
-			    h5offset[1] = (nbytes_xfer%(snbytes*blk_size))/blk_size;
-			} /* end if */
-			else {
-			    /* Interleaved access pattern */
-			    /* Skip offset over blocks of other processes */
-			    h5offset[0] = ((nbytes_xfer*pio_mpi_nprocs_g)/(snbytes*buf_size))*buf_size;
-			    h5offset[1] = ((nbytes_xfer*pio_mpi_nprocs_g)%(snbytes*buf_size))/buf_size;
-
-			} /* end else */
-			hrc = H5Soffset_simple(h5dset_space_id, h5offset);
-			VRFY((hrc >= 0), "H5Soffset_simple");
-
-			/* Write the buffer out */
-			hrc = H5Dread(h5ds_id, ELMT_H5_TYPE, h5mem_space_id,
-				h5dset_space_id, h5dxpl, buffer);
-			VRFY((hrc >= 0), "H5Dread");
-
-			/* Increment number of bytes transferred */
-			nbytes_xfer += buf_size*blk_size;
-
-		    } /* end else */
-		    break;
-	    } /* switch (parms->io_type) */
-
-	    /* Verify raw data, if asked */
-	    if (parms->verify) {
-		/* Verify data read */
-		unsigned char *ucharptr = (unsigned char *)buffer;
-		size_t i;
-		int nerror=0;
-
-		for (i = 0; i < bsize; ++i){
-		    if (*ucharptr++ != pio_mpi_rank_g+1) {
-			if (++nerror < 20){
-			    /* report at most 20 errors */
-			    HDprint_rank(output);
-			    HDfprintf(output, "read data error, expected (%Hd), "
-				    "got (%Hd)\n",
-				    (long_long)pio_mpi_rank_g+1,
-				    (long_long)*(ucharptr-1));
-			} /* end if */
-		    } /* end if */
-		} /* end for */
-		if (nerror >= 20) {
-		    HDprint_rank(output);
-		    HDfprintf(output, "...");
-		    HDfprintf(output, "total read data errors=%d\n",
-			    nerror);
-		} /* end if */
-	    }	/* if (parms->verify) */
-
-	} /* end while */
-
-	/* Stop "raw data" read timer */
-	set_time(res->timers, HDF5_RAW_READ_FIXED_DIMS, STOP);
-
-	/* Calculate read time */
-
-	/* Close dataset. Only HDF5 needs to do an explicit close. */
-	if (parms->io_type == PHDF5) {
-	    hrc = H5Dclose(h5ds_id);
-
-	    if (hrc < 0) {
-		fprintf(stderr, "HDF5 Dataset Close failed\n");
-		GOTOERROR(FAIL);
-	    }
-
-	    h5ds_id = -1;
-	} /* end if */
+    for (ndset = 1; ndset <= ndsets; ++ndset) {
+
+    /* Calculate dataset offset within a file */
+
+    /* create dataset */
+    switch (parms->io_type) {
+        case POSIXIO:
+        case MPIO:
+        /* both posix and mpi io just need dataset offset in file*/
+        dset_offset = (ndset - 1) * nbytes;
+        break;
+
+        case PHDF5:
+        sprintf(dname, "Dataset_%ld", ndset);
+        h5ds_id = H5Dopen2(fd->h5fd, dname, H5P_DEFAULT);
+        if (h5ds_id < 0) {
+            fprintf(stderr, "HDF5 Dataset open failed\n");
+            GOTOERROR(FAIL);
+        }
+
+        break;
+    }
+
+    /* The task is to transfer bytes_count bytes, starting at
+     * bytes_begin position, using transfer buffer of buf_size bytes.
+     * If interleaved, select buf_size at a time, in round robin
+     * fashion, according to number of process. Otherwise, select
+     * all bytes_count in contiguous.
+     */
+    nbytes_xfer = 0 ;
+
+    /* 1D dataspace */
+    if (!parms->dim2d){
+        /* Set base file offset for all I/O patterns and POSIX access */
+        posix_file_offset = dset_offset + bytes_begin[0];
+
+        /* Set base file offset for all I/O patterns and MPI access */
+        mpi_file_offset = (MPI_Offset)(dset_offset + bytes_begin[0]);
+    } /* end if */
+    else {
+        /* Set base file offset for all I/O patterns and POSIX access */
+        posix_file_offset=dset_offset + bytes_begin[0]*snbytes+
+        bytes_begin[1];
+
+        /* Set base file offset for all I/O patterns and MPI access */
+        mpi_file_offset=(MPI_Offset)(dset_offset + bytes_begin[0]*snbytes+
+            bytes_begin[1]);
+    } /* end else */
+
+    /* Start "raw data" read timer */
+    set_time(res->timers, HDF5_RAW_READ_FIXED_DIMS, START);
+
+    while (nbytes_xfer < bytes_count){
+        /* Read */
+        /* Calculate offset of read within a dataset/file */
+        switch (parms->io_type) {
+        case POSIXIO:
+            /* 1D dataspace */
+            if (!parms->dim2d){
+                /* Contiguous pattern */
+                if (!parms->interleaved) {
+                    /* Compute file offset */
+                    file_offset = posix_file_offset + (off_t)nbytes_xfer;
+
+                    /* only care if seek returns error */
+                    rc = POSIXSEEK(fd->posixfd, file_offset) < 0 ? -1 : 0;
+                    VRFY((rc==0), "POSIXSEEK");
+
+                    /* check if all bytes are read */
+                    rc = ((ssize_t)buf_size ==
+                        POSIXREAD(fd->posixfd, buffer, buf_size));
+                    VRFY((rc != 0), "POSIXREAD");
+
+                    /* Advance global offset in dataset */
+                    nbytes_xfer+=buf_size;
+                } /* end if */
+                /* Interleaved access pattern */
+                else {
+                    /* Set the base of user's buffer */
+                    buf_p=(unsigned char *)buffer;
+
+                    /* Set the number of bytes to transfer this time */
+                    nbytes_toxfer = buf_size;
+
+                    /* Loop over the buffers to read */
+                    while(nbytes_toxfer>0) {
+                    /* Skip offset over blocks of other processes */
+                    file_offset = posix_file_offset +
+                        (off_t)(nbytes_xfer*pio_mpi_nprocs_g);
+
+                    /* only care if seek returns error */
+                    rc = POSIXSEEK(fd->posixfd, file_offset) < 0 ? -1 : 0;
+                    VRFY((rc==0), "POSIXSEEK");
+
+                    /* check if all bytes are read */
+                    rc = ((ssize_t)blk_size ==
+                        POSIXREAD(fd->posixfd, buf_p, blk_size));
+                    VRFY((rc != 0), "POSIXREAD");
+
+                    /* Advance location in buffer */
+                    buf_p+=blk_size;
+
+                    /* Advance global offset in dataset */
+                    nbytes_xfer+=blk_size;
+
+                    /* Decrement number of bytes left this time */
+                    nbytes_toxfer-=blk_size;
+                    } /* end while */
+                } /* end else */
+            } /* end if */
+            /* 2D dataspace */
+            else {
+                /* Contiguous storage */
+                if (!parms->h5_use_chunks) {
+                    /* Contiguous access pattern */
+                    if (!parms->interleaved) {
+                        /* Compute file offset */
+                        file_offset=posix_file_offset+(off_t)(((nbytes_xfer/blk_size)
+                            /snbytes)*(blk_size*snbytes)+((nbytes_xfer/blk_size)%snbytes));
+
+                        /* Number of bytes to be transferred per I/O operation */
+                        nbytes_xfer_advance = buf_size;
+
+                        /* Global offset advance after each I/O operation */                            
+                        file_offset_advance = (off_t)snbytes;
+                    } /* end if */
+                    /* Interleaved access pattern */
+                    else {
+                        /* Compute file offset */
+                        file_offset=posix_file_offset+(off_t)((((nbytes_xfer/buf_size)
+                            *pio_mpi_nprocs_g)/snbytes)*(buf_size*snbytes)
+                            +((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)%snbytes);
+
+                        /* Number of bytes to be transferred per I/O operation */
+                        nbytes_xfer_advance = blk_size;
+
+                        /* Global offset advance after each I/O operation */                            
+                        file_offset_advance = (off_t)snbytes;
+                    } /* end else */
+                } /* end if */
+                /* Chunked storage */
+                else {
+                    /*Contiguous access pattern */
+                    if (!parms->interleaved) {
+                        /* Compute file offset */
+                        file_offset=posix_file_offset+(off_t)nbytes_xfer;
+
+                        /* Number of bytes to be transferred per I/O operation */
+                        nbytes_xfer_advance = blk_size * buf_size;
+
+                        /* Global offset advance after each I/O operation */                            
+                        file_offset_advance = 0;
+                    } /* end if */
+                    /*Interleaved access pattern */
+                    else {
+                        /* Compute file offset */
+                        /* Before simplification */
+                        /* file_offset=posix_file_offset+(off_t)((nbytes_xfer/(buf_size/blk_size)
+                        *pio_mpi_nprocs_g)/(snbytes/blk_size*(blk_size*blk_size))*(buf_size/blk_size
+                        *snbytes/blk_size*(blk_size*blk_size))+((nbytes_xfer/(buf_size/blk_size))
+                        *pio_mpi_nprocs_g)%(snbytes/blk_size*(blk_size*blk_size))); */
+
+                        file_offset=posix_file_offset+(off_t)(((nbytes_xfer/(buf_size/blk_size)
+                        *pio_mpi_nprocs_g)/(snbytes*blk_size))*(buf_size*snbytes)+((nbytes_xfer/(buf_size/blk_size))
+                        *pio_mpi_nprocs_g)%(snbytes*blk_size));
+
+                        /* Number of bytes to be transferred per I/O operation */
+                        nbytes_xfer_advance = blk_size * blk_size;
+
+                        /* Global offset advance after each I/O operation */                            
+                        /* file_offset_advance = (off_t)(snbytes/blk_size*(blk_size*blk_size)); */
+                        file_offset_advance = (off_t)(snbytes*blk_size);
+                    } /* end else */
+                } /* end else */
+
+                /* Common code for file access */
+
+                /* Set the base of user's buffer */
+                buf_p = (unsigned char *)buffer;
+
+                /* Set the number of bytes to transfer this time */
+                nbytes_toxfer = buf_size*blk_size;
+
+                /* Loop over portions of the buffer to read */
+                while(nbytes_toxfer>0){
+                    /* only care if seek returns error */
+                    rc = POSIXSEEK(fd->posixfd, file_offset) < 0 ? -1 : 0;
+                    VRFY((rc==0), "POSIXSEEK");
+
+                    /* check if all bytes are read */
+                    rc = ((ssize_t)nbytes_xfer_advance ==
+                        POSIXREAD(fd->posixfd, buf_p, nbytes_xfer_advance));
+                    VRFY((rc != 0), "POSIXREAD");
+
+                    /* Advance location in buffer */
+                    buf_p+=nbytes_xfer_advance;
+
+                    /* Advance global offset in dataset */
+                    nbytes_xfer+=nbytes_xfer_advance;
+
+                    /* Decrement number of bytes left this time */
+                    nbytes_toxfer-=nbytes_xfer_advance;
+
+                    /* Partially advance file offset */
+                    file_offset+=file_offset_advance;
+                } /* end while */
+
+            } /* end else */
+            break;
+
+        case MPIO:
+            /* 1D dataspace */
+            if (!parms->dim2d){
+                /* Independent file access */
+                if(!parms->collective) {
+                    /* Contiguous pattern */
+                    if (!parms->interleaved){
+                        /* Compute offset in file */
+                        mpi_offset = mpi_file_offset +
+                            nbytes_xfer;
+
+                        /* Perform independent read */
+                        mrc = MPI_File_read_at(fd->mpifd, mpi_offset, buffer,
+                            (int)(buf_size/blk_size), mpi_blk_type,
+                            &mpi_status);
+                        VRFY((mrc==MPI_SUCCESS), "MPIO_READ");
+
+                        /* Advance global offset in dataset */
+                        nbytes_xfer+=buf_size;
+                    } /* end if */
+                    /* Interleaved access pattern */
+                    else {
+                        /* Set the base of user's buffer */
+                        buf_p=(unsigned char *)buffer;
+
+                        /* Set the number of bytes to transfer this time */
+                        nbytes_toxfer = buf_size;
+
+                        /* Loop over the buffers to read */
+                        while(nbytes_toxfer>0) {
+                            /* Skip offset over blocks of other processes */
+                            mpi_offset = mpi_file_offset +
+                            (nbytes_xfer*pio_mpi_nprocs_g);
+
+                            /* Perform independent read */
+                            mrc = MPI_File_read_at(fd->mpifd, mpi_offset, buf_p,
+                                (int)1, mpi_blk_type, &mpi_status);
+                            VRFY((mrc==MPI_SUCCESS), "MPIO_READ");
+
+                            /* Advance location in buffer */
+                            buf_p+=blk_size;
+
+                            /* Advance global offset in dataset */
+                            nbytes_xfer+=blk_size;
+
+                            /* Decrement number of bytes left this time */
+                            nbytes_toxfer-=blk_size;
+                        } /* end while */
+                    } /* end else */
+                } /* end if */
+                /* Collective file access */
+                else {
+                    /* Contiguous access pattern */
+                    if (!parms->interleaved){
+                        /* Compute offset in file */
+                        mpi_offset = mpi_file_offset +
+                            nbytes_xfer;
+
+                        /* Perform collective read */
+                        mrc = MPI_File_read_at_all(fd->mpifd, mpi_offset, buffer,
+                            (int)(buf_size/blk_size), mpi_blk_type, &mpi_status);
+                        VRFY((mrc==MPI_SUCCESS), "MPIO_READ");
+
+                        /* Advance global offset in dataset */
+                        nbytes_xfer+=buf_size;
+                    } /* end if */
+                    /* Interleaved access pattern */
+                    else {
+                        /* Compute offset in file */
+                        mpi_offset = mpi_file_offset +
+                            (nbytes_xfer*pio_mpi_nprocs_g);
+
+                        /* Set the file view */
+                        mrc = MPI_File_set_view(fd->mpifd, mpi_offset, mpi_blk_type,
+                            mpi_file_type, (char*)"native",  h5_io_info_g);
+                        VRFY((mrc==MPI_SUCCESS), "MPIO_VIEW");
+
+                        /* Perform collective read */
+                        mrc = MPI_File_read_at_all(fd->mpifd, 0, buffer,
+                            (int)(buf_size/blk_size), mpi_blk_type, &mpi_status);
+                        VRFY((mrc==MPI_SUCCESS), "MPIO_READ");
+
+                        /* Advance global offset in dataset */
+                        nbytes_xfer+=buf_size;
+                    } /* end else */
+                } /* end else */
+            } /* end if */
+            /* 2D dataspace */
+            else {
+                /* Contiguous storage */
+                if (!parms->h5_use_chunks) {
+                    /* Contiguous access pattern */
+                    if (!parms->interleaved) {
+                        /* Compute offset in file */
+                        mpi_offset=mpi_file_offset+((nbytes_xfer/blk_size)/snbytes)*
+                            (blk_size*snbytes)+((nbytes_xfer/blk_size)%snbytes);
+
+                        /* Number of bytes to be transferred per I/O operation */
+                        nbytes_xfer_advance = buf_size;
+
+                        /* Global offset advance after each I/O operation */                            
+                        mpi_offset_advance = snbytes;
+
+                        /* MPI type to be used for collective access */
+                        mpi_collective_type = mpi_cont_type;
+                    } /* end if */
+                    /* Interleaved access pattern */
+                    else {
+                        /* Compute offset in file */
+                        mpi_offset=mpi_file_offset+(((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)/snbytes)*
+                            (buf_size*snbytes)+((nbytes_xfer/buf_size)*pio_mpi_nprocs_g)%snbytes;
+
+                        /* Number of bytes to be transferred per I/O operation */
+                        nbytes_xfer_advance = blk_size;
+
+                        /* Global offset advance after each I/O operation */                            
+                        mpi_offset_advance = snbytes;
+
+                        /* MPI type to be used for collective access */
+                        mpi_collective_type = mpi_inter_type;
+                    } /* end else */
+                } /* end if */
+                /* Chunked storage */
+                else {
+                    /*Contiguous access pattern */
+                    if (!parms->interleaved) {
+                        /* Compute offset in file */
+                        mpi_offset=mpi_file_offset+nbytes_xfer;
+
+                        /* Number of bytes to be transferred per I/O operation */
+                        nbytes_xfer_advance = blk_size * buf_size;
+
+                        /* Global offset advance after each I/O operation */                            
+                        mpi_offset_advance = 0;
+
+                        /* MPI type to be used for collective access */
+                        mpi_collective_type = mpi_full_buffer;
+                    } /* end if */
+                    /*Interleaved access pattern */
+                    else {
+                        /* Compute offset in file */
+                        /* Before simplification */
+                        /* mpi_offset=mpi_file_offset+(nbytes_xfer/(buf_size/blk_size)
+                            *pio_mpi_nprocs_g)/(snbytes/blk_size*(blk_size*blk_size))*
+                            (buf_size/blk_size*snbytes/blk_size*(blk_size*blk_size))+
+                            ((nbytes_xfer/(buf_size/blk_size))*pio_mpi_nprocs_g)%(snbytes
+                            /blk_size*(blk_size*blk_size)); */
+                        mpi_offset=mpi_file_offset+((nbytes_xfer/(buf_size/blk_size)
+                            *pio_mpi_nprocs_g)/(snbytes*blk_size))*(buf_size*snbytes)
+                            +((nbytes_xfer/(buf_size/blk_size))*pio_mpi_nprocs_g)%(snbytes*blk_size);
+
+                        /* Number of bytes to be transferred per I/O operation */
+                        nbytes_xfer_advance = blk_size * blk_size;
+
+                        /* Global offset advance after each I/O operation */                            
+                        /* mpi_offset_advance = (MPI_Offset)(snbytes/blk_size*(blk_size*blk_size)); */
+                        mpi_offset_advance = (MPI_Offset)(snbytes*blk_size);
+
+                        /* MPI type to be used for collective access */
+                        mpi_collective_type = mpi_chunk_inter_type;
+                    } /* end else */
+                } /* end else */
+
+                /* Common code for independent file access */
+                if (!parms->collective) {
+                    /* Set the base of user's buffer */
+                    buf_p = (unsigned char *)buffer;
+
+                    /* Set the number of bytes to transfer this time */
+                    nbytes_toxfer = buf_size * blk_size;
+
+                    /* Loop over portions of the buffer to read */
+                    while(nbytes_toxfer>0){
+                        /* Perform independent read */
+                        mrc = MPI_File_read_at(fd->mpifd, mpi_offset, buf_p,
+                            (int)nbytes_xfer_advance, MPI_BYTE, &mpi_status);
+                        VRFY((mrc==MPI_SUCCESS), "MPIO_READ");
+
+                        /* Advance location in buffer */
+                        buf_p+=nbytes_xfer_advance;
+
+                        /* Advance global offset in dataset */
+                        nbytes_xfer+=nbytes_xfer_advance;
+
+                        /* Decrement number of bytes left this time */
+                        nbytes_toxfer-=nbytes_xfer_advance;
+
+                        /* Partially advance global offset in dataset */
+                        mpi_offset+=mpi_offset_advance;
+                    } /* end while */
+                } /* end if */
+
+                /* Common code for collective file access */
+                else {
+                    /* Set the file view */
+                    mrc = MPI_File_set_view(fd->mpifd, mpi_offset, MPI_BYTE,
+                        mpi_collective_type, (char *)"native", h5_io_info_g);
+                    VRFY((mrc==MPI_SUCCESS), "MPIO_VIEW");
+
+                    /* Perform read */
+                    MPI_File_read_at_all(fd->mpifd, 0, buffer,(int)(buf_size*blk_size),
+                        MPI_BYTE, &mpi_status);
+                    VRFY((mrc==MPI_SUCCESS), "MPIO_READ");
+
+                    /* Advance global offset in dataset */
+                    nbytes_xfer+=buf_size*blk_size;
+                } /* end else */
+
+            } /* end else */
+            break;
+
+        case PHDF5:
+            /* 1D dataspace */
+            if (!parms->dim2d){
+            /* Set up the file dset space id to move the selection to process */
+            if (!parms->interleaved){
+                /* Contiguous pattern */
+                h5offset[0] = nbytes_xfer;
+            } /* end if */
+            else {
+                /* Interleaved access pattern */
+                /* Skip offset over blocks of other processes */
+                h5offset[0] = (nbytes_xfer*pio_mpi_nprocs_g);
+            } /* end else */
+            hrc = H5Soffset_simple(h5dset_space_id, h5offset);
+            VRFY((hrc >= 0), "H5Soffset_simple");
+
+            /* Read the buffer in */
+            hrc = H5Dread(h5ds_id, ELMT_H5_TYPE, h5mem_space_id,
+                h5dset_space_id, h5dxpl, buffer);
+            VRFY((hrc >= 0), "H5Dread");
+
+            /* Increment number of bytes transferred */
+            nbytes_xfer += buf_size;
+            } /* end if */
+            /* 2D dataspace */
+            else {
+            /* Set up the file dset space id to move the selection to process */
+            if (!parms->interleaved){
+                /* Contiguous pattern */
+                h5offset[0] = (nbytes_xfer/(snbytes*blk_size))*blk_size;
+                h5offset[1] = (nbytes_xfer%(snbytes*blk_size))/blk_size;
+            } /* end if */
+            else {
+                /* Interleaved access pattern */
+                /* Skip offset over blocks of other processes */
+                h5offset[0] = ((nbytes_xfer*pio_mpi_nprocs_g)/(snbytes*buf_size))*buf_size;
+                h5offset[1] = ((nbytes_xfer*pio_mpi_nprocs_g)%(snbytes*buf_size))/buf_size;
+
+            } /* end else */
+            hrc = H5Soffset_simple(h5dset_space_id, h5offset);
+            VRFY((hrc >= 0), "H5Soffset_simple");
+
+            /* Write the buffer out */
+            hrc = H5Dread(h5ds_id, ELMT_H5_TYPE, h5mem_space_id,
+                h5dset_space_id, h5dxpl, buffer);
+            VRFY((hrc >= 0), "H5Dread");
+
+            /* Increment number of bytes transferred */
+            nbytes_xfer += buf_size*blk_size;
+
+            } /* end else */
+            break;
+        } /* switch (parms->io_type) */
+
+        /* Verify raw data, if asked */
+        if (parms->verify) {
+        /* Verify data read */
+        unsigned char *ucharptr = (unsigned char *)buffer;
+        size_t i;
+        int nerror=0;
+
+        for (i = 0; i < bsize; ++i){
+            if (*ucharptr++ != pio_mpi_rank_g+1) {
+            if (++nerror < 20){
+                /* report at most 20 errors */
+                HDprint_rank(output);
+                HDfprintf(output, "read data error, expected (%Hd), "
+                    "got (%Hd)\n",
+                    (long_long)pio_mpi_rank_g+1,
+                    (long_long)*(ucharptr-1));
+            } /* end if */
+            } /* end if */
+        } /* end for */
+        if (nerror >= 20) {
+            HDprint_rank(output);
+            HDfprintf(output, "...");
+            HDfprintf(output, "total read data errors=%d\n",
+                nerror);
+        } /* end if */
+        }   /* if (parms->verify) */
+
+    } /* end while */
+
+    /* Stop "raw data" read timer */
+    set_time(res->timers, HDF5_RAW_READ_FIXED_DIMS, STOP);
+
+    /* Calculate read time */
+
+    /* Close dataset. Only HDF5 needs to do an explicit close. */
+    if (parms->io_type == PHDF5) {
+        hrc = H5Dclose(h5ds_id);
+
+        if (hrc < 0) {
+        fprintf(stderr, "HDF5 Dataset Close failed\n");
+        GOTOERROR(FAIL);
+        }
+
+        h5ds_id = -1;
+    } /* end if */
     } /* end for */
 
 done:
     /* release MPI-I/O objects */
     if (parms->io_type == MPIO) {
-	/* 1D dataspace */
-	if (parms->dim2d==0){
-	    /* Free file type */
-	    mrc = MPI_Type_free( &mpi_file_type );
-	    VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
-
-	    /* Free buffer type */
-	    mrc = MPI_Type_free( &mpi_blk_type );
-	    VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
-	} /* end if */
-	/* 2D dataspace */
-	else {
-	    /* Free file type */
-	    mrc = MPI_Type_free( &mpi_cont_type );
-	    VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
-
-	    /* Free partial buffer type */
-	    mrc = MPI_Type_free( &contig_cont );
-	    VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
-
-	    /* Free file type */
-	    mrc = MPI_Type_free( &mpi_inter_type );
-	    VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
-
-	    /* Free partial buffer type */
-	    mrc = MPI_Type_free( &contig_inter );
-	    VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
-	} /* end else */
+        /* 1D dataspace */
+        if (!parms->dim2d){
+            /* Free file type */
+            mrc = MPI_Type_free( &mpi_file_type );
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+
+            /* Free buffer type */
+            mrc = MPI_Type_free( &mpi_blk_type );
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+        } /* end if */
+        /* 2D dataspace */
+        else {
+            /* Free partial buffer type for contiguous access */
+            mrc = MPI_Type_free( &mpi_partial_buffer_cont );
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+
+            /* Free contiguous file type */
+            mrc = MPI_Type_free( &mpi_cont_type );
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+
+            /* Free partial buffer type for interleaved access */
+            mrc = MPI_Type_free( &mpi_partial_buffer_inter );
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+
+            /* Free interleaved file type */
+            mrc = MPI_Type_free( &mpi_inter_type );
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+
+            /* Free full buffer type */
+            mrc = MPI_Type_free(&mpi_full_buffer);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+
+            /* Free full chunk type */
+            mrc = MPI_Type_free(&mpi_full_chunk);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+        
+            /* Free chunk interleaved file type */
+            mrc = MPI_Type_free(&mpi_chunk_inter_type);
+            VRFY((mrc==MPI_SUCCESS), "MPIO_TYPE_FREE");
+        } /* end else */
     } /* end if */
 
     /* release HDF5 objects */
     if (h5dset_space_id != -1) {
-	hrc = H5Sclose(h5dset_space_id);
-	if (hrc < 0){
-	    fprintf(stderr, "HDF5 Dataset Space Close failed\n");
-	    ret_code = FAIL;
-	} else {
-	    h5dset_space_id = -1;
-	}
+    hrc = H5Sclose(h5dset_space_id);
+    if (hrc < 0){
+        fprintf(stderr, "HDF5 Dataset Space Close failed\n");
+        ret_code = FAIL;
+    } else {
+        h5dset_space_id = -1;
+    }
     }
 
     if (h5mem_space_id != -1) {
-	hrc = H5Sclose(h5mem_space_id);
-	if (hrc < 0) {
-	    fprintf(stderr, "HDF5 Memory Space Close failed\n");
-	    ret_code = FAIL;
-	} else {
-	    h5mem_space_id = -1;
-	}
+    hrc = H5Sclose(h5mem_space_id);
+    if (hrc < 0) {
+        fprintf(stderr, "HDF5 Memory Space Close failed\n");
+        ret_code = FAIL;
+    } else {
+        h5mem_space_id = -1;
+    }
     }
 
     if (h5dxpl != -1) {
-	hrc = H5Pclose(h5dxpl);
-	if (hrc < 0) {
-	    fprintf(stderr, "HDF5 Dataset Transfer Property List Close failed\n");
-	    ret_code = FAIL;
-	} else {
-	    h5dxpl = -1;
-	}
+    hrc = H5Pclose(h5dxpl);
+    if (hrc < 0) {
+        fprintf(stderr, "HDF5 Dataset Transfer Property List Close failed\n");
+        ret_code = FAIL;
+    } else {
+        h5dxpl = -1;
+    }
     }
 
     return ret_code;
@@ -2230,115 +2443,115 @@ do_fopen(parameters *param, char *fname, file_descr *fd /*out*/, int flags)
     hbool_t use_gpfs = FALSE;   /* use GPFS hints        */
 
     switch (param->io_type) {
-	case POSIXIO:
-	    if (flags & (PIO_CREATE | PIO_WRITE))
-		fd->posixfd = POSIXCREATE(fname);
-	    else
-		fd->posixfd = POSIXOPEN(fname, O_RDONLY);
-
-	    if (fd->posixfd < 0 ) {
-		fprintf(stderr, "POSIX File Open failed(%s)\n", fname);
-		GOTOERROR(FAIL);
-	    }
-
-
-	    /* The perils of POSIX I/O in a parallel environment. The problem is:
-	     *
-	     *      - Process n opens a file with truncation and then starts
-	     *        writing to the file.
-	     *      - Process m also opens the file with truncation, but after
-	     *        process n has already started to write to the file. Thus,
-	     *        all of the stuff process n wrote is now lost.
-	     */
-	    MPI_Barrier(pio_comm_g);
-
-	    break;
-
-	case MPIO:
-	    if (flags & (PIO_CREATE | PIO_WRITE)) {
-		MPI_File_delete(fname, h5_io_info_g);
-		mrc = MPI_File_open(pio_comm_g, fname, MPI_MODE_CREATE | MPI_MODE_RDWR,
-			h5_io_info_g, &fd->mpifd);
-
-		if (mrc != MPI_SUCCESS) {
-		    fprintf(stderr, "MPI File Open failed(%s)\n", fname);
-		    GOTOERROR(FAIL);
-		}
-
-		/*since MPI_File_open with MPI_MODE_CREATE does not truncate  */
-		/*filesize , set size to 0 explicitedly.	*/
-		mrc = MPI_File_set_size(fd->mpifd, (MPI_Offset)0);
-
-		if (mrc != MPI_SUCCESS) {
-		    fprintf(stderr, "MPI_File_set_size failed\n");
-		    GOTOERROR(FAIL);
-		}
-	    } else {
-		mrc = MPI_File_open(pio_comm_g, fname, MPI_MODE_RDONLY,
-			h5_io_info_g, &fd->mpifd);
-
-		if (mrc != MPI_SUCCESS) {
-		    fprintf(stderr, "MPI File Open failed(%s)\n", fname);
-		    GOTOERROR(FAIL);
-		}
-	    }
-
-	    break;
-
-	case PHDF5:
-	    acc_tpl = H5Pcreate(H5P_FILE_ACCESS);
-	    if (acc_tpl < 0) {
-		fprintf(stderr, "HDF5 Property List Create failed\n");
-		GOTOERROR(FAIL);
-	    }
-
-	    /* Use the appropriate VFL driver */
-	    if(param->h5_use_mpi_posix) {
-		/* Set the file driver to the MPI-posix driver */
-		hrc = H5Pset_fapl_mpiposix(acc_tpl, pio_comm_g, use_gpfs);
-		if (hrc < 0) {
-		    fprintf(stderr, "HDF5 Property List Set failed\n");
-		    GOTOERROR(FAIL);
-		}
-	    } /* end if */
-	    else {
-		/* Set the file driver to the MPI-I/O driver */
-		hrc = H5Pset_fapl_mpio(acc_tpl, pio_comm_g, h5_io_info_g);
-		if (hrc < 0) {
-		    fprintf(stderr, "HDF5 Property List Set failed\n");
-		    GOTOERROR(FAIL);
-		}
-	    } /* end else */
-
-	    /* Set the alignment of objects in HDF5 file */
-	    hrc = H5Pset_alignment(acc_tpl, param->h5_thresh, param->h5_align);
-	    if (hrc < 0) {
-		fprintf(stderr, "HDF5 Property List Set failed\n");
-		GOTOERROR(FAIL);
-	    }
-
-	    /* create the parallel file */
-	    if (flags & (PIO_CREATE | PIO_WRITE)) {
-		fd->h5fd = H5Fcreate(fname, H5F_ACC_TRUNC, H5P_DEFAULT, acc_tpl);
-	    } else {
-		fd->h5fd = H5Fopen(fname, H5F_ACC_RDONLY, acc_tpl);
-	    }
-
-	    hrc = H5Pclose(acc_tpl);
-
-	    if (fd->h5fd < 0) {
-		fprintf(stderr, "HDF5 File Create failed(%s)\n", fname);
-		GOTOERROR(FAIL);
-	    }
-
-	    /* verifying the close of the acc_tpl */
-	    if (hrc < 0) {
-		fprintf(stderr, "HDF5 Property List Close failed\n");
-		GOTOERROR(FAIL);
-	    }
-
-	    break;
-    }
+    case POSIXIO:
+        if (flags & (PIO_CREATE | PIO_WRITE))
+        fd->posixfd = POSIXCREATE(fname);
+        else
+        fd->posixfd = POSIXOPEN(fname, O_RDONLY);
+
+        if (fd->posixfd < 0 ) {
+        fprintf(stderr, "POSIX File Open failed(%s)\n", fname);
+        GOTOERROR(FAIL);
+        }
+
+
+        /* The perils of POSIX I/O in a parallel environment. The problem is:
+         *
+         *      - Process n opens a file with truncation and then starts
+         *        writing to the file.
+         *      - Process m also opens the file with truncation, but after
+         *        process n has already started to write to the file. Thus,
+         *        all of the stuff process n wrote is now lost.
+         */
+        MPI_Barrier(pio_comm_g);
+
+        break;
+
+    case MPIO:
+        if (flags & (PIO_CREATE | PIO_WRITE)) {
+        MPI_File_delete(fname, h5_io_info_g);
+        mrc = MPI_File_open(pio_comm_g, fname, MPI_MODE_CREATE | MPI_MODE_RDWR,
+            h5_io_info_g, &fd->mpifd);
+
+        if (mrc != MPI_SUCCESS) {
+            fprintf(stderr, "MPI File Open failed(%s)\n", fname);
+            GOTOERROR(FAIL);
+        }
+
+        /*since MPI_File_open with MPI_MODE_CREATE does not truncate  */
+        /*filesize , set size to 0 explicitedly.    */
+        mrc = MPI_File_set_size(fd->mpifd, (MPI_Offset)0);
+
+        if (mrc != MPI_SUCCESS) {
+            fprintf(stderr, "MPI_File_set_size failed\n");
+            GOTOERROR(FAIL);
+        }
+        } else {
+        mrc = MPI_File_open(pio_comm_g, fname, MPI_MODE_RDONLY,
+            h5_io_info_g, &fd->mpifd);
+
+        if (mrc != MPI_SUCCESS) {
+            fprintf(stderr, "MPI File Open failed(%s)\n", fname);
+            GOTOERROR(FAIL);
+        }
+        }
+
+        break;
+
+    case PHDF5:
+        acc_tpl = H5Pcreate(H5P_FILE_ACCESS);
+        if (acc_tpl < 0) {
+        fprintf(stderr, "HDF5 Property List Create failed\n");
+        GOTOERROR(FAIL);
+        }
+
+        /* Use the appropriate VFL driver */
+        if(param->h5_use_mpi_posix) {
+        /* Set the file driver to the MPI-posix driver */
+        hrc = H5Pset_fapl_mpiposix(acc_tpl, pio_comm_g, use_gpfs);
+        if (hrc < 0) {
+            fprintf(stderr, "HDF5 Property List Set failed\n");
+            GOTOERROR(FAIL);
+        }
+        } /* end if */
+        else {
+        /* Set the file driver to the MPI-I/O driver */
+        hrc = H5Pset_fapl_mpio(acc_tpl, pio_comm_g, h5_io_info_g);
+        if (hrc < 0) {
+            fprintf(stderr, "HDF5 Property List Set failed\n");
+            GOTOERROR(FAIL);
+        }
+        } /* end else */
+
+        /* Set the alignment of objects in HDF5 file */
+        hrc = H5Pset_alignment(acc_tpl, param->h5_thresh, param->h5_align);
+        if (hrc < 0) {
+        fprintf(stderr, "HDF5 Property List Set failed\n");
+        GOTOERROR(FAIL);
+        }
+
+        /* create the parallel file */
+        if (flags & (PIO_CREATE | PIO_WRITE)) {
+        fd->h5fd = H5Fcreate(fname, H5F_ACC_TRUNC, H5P_DEFAULT, acc_tpl);
+        } else {
+        fd->h5fd = H5Fopen(fname, H5F_ACC_RDONLY, acc_tpl);
+        }
+
+        hrc = H5Pclose(acc_tpl);
+
+        if (fd->h5fd < 0) {
+        fprintf(stderr, "HDF5 File Create failed(%s)\n", fname);
+        GOTOERROR(FAIL);
+        }
+
+        /* verifying the close of the acc_tpl */
+        if (hrc < 0) {
+        fprintf(stderr, "HDF5 Property List Close failed\n");
+        GOTOERROR(FAIL);
+        }
+
+        break;
+    } 
 
 done:
     return ret_code;
@@ -2358,38 +2571,38 @@ do_fclose(iotype iot, file_descr *fd /*out*/)
     int mrc = 0, rc = 0;
 
     switch (iot) {
-	case POSIXIO:
-	    rc = POSIXCLOSE(fd->posixfd);
+    case POSIXIO:
+        rc = POSIXCLOSE(fd->posixfd);
 
-	    if (rc != 0){
-		fprintf(stderr, "POSIX File Close failed\n");
-		GOTOERROR(FAIL);
-	    }
+        if (rc != 0){
+        fprintf(stderr, "POSIX File Close failed\n");
+        GOTOERROR(FAIL);
+        }
 
-	    fd->posixfd = -1;
-	    break;
+        fd->posixfd = -1;
+        break;
 
-	case MPIO:
-	    mrc = MPI_File_close(&fd->mpifd);
+    case MPIO:
+        mrc = MPI_File_close(&fd->mpifd);
 
-	    if (mrc != MPI_SUCCESS){
-		fprintf(stderr, "MPI File close failed\n");
-		GOTOERROR(FAIL);
-	    }
+        if (mrc != MPI_SUCCESS){
+        fprintf(stderr, "MPI File close failed\n");
+        GOTOERROR(FAIL);
+        }
 
-	    fd->mpifd = MPI_FILE_NULL;
-	    break;
+        fd->mpifd = MPI_FILE_NULL;
+        break;
 
-	case PHDF5:
-	    hrc = H5Fclose(fd->h5fd);
+    case PHDF5:
+        hrc = H5Fclose(fd->h5fd);
 
-	    if (hrc < 0) {
-		fprintf(stderr, "HDF5 File Close failed\n");
-		GOTOERROR(FAIL);
-	    }
+        if (hrc < 0) {
+        fprintf(stderr, "HDF5 File Close failed\n");
+        GOTOERROR(FAIL);
+        }
 
-	    fd->h5fd = -1;
-	    break;
+        fd->h5fd = -1;
+        break;
     }
 
 done:
@@ -2400,8 +2613,8 @@ done:
 /*
  * Function:    do_fclose
  * Purpose:     Cleanup temporary file unless HDF5_NOCLEANUP is set.
- * 		Only Proc 0 of the PIO communicator will do the cleanup.
- *		Other processes just return.
+ *      Only Proc 0 of the PIO communicator will do the cleanup.
+ *      Other processes just return.
  * Return:      void
  * Programmer:  Albert Cheng 2001/12/12
  * Modifications:
@@ -2410,21 +2623,21 @@ done:
 do_cleanupfile(iotype iot, char *fname)
 {
     if (pio_mpi_rank_g != 0)
-	return;
+    return;
 
     if (clean_file_g == -1)
-	clean_file_g = (getenv("HDF5_NOCLEANUP")==NULL) ? 1 : 0;
+    clean_file_g = (getenv("HDF5_NOCLEANUP")==NULL) ? 1 : 0;
 
     if (clean_file_g){
-	switch (iot){
-	    case POSIXIO:
-		remove(fname);
-		break;
-	    case MPIO:
-	    case PHDF5:
-		MPI_File_delete(fname, h5_io_info_g);
-		break;
-	}
+    switch (iot){
+        case POSIXIO:
+        remove(fname);
+        break;
+        case MPIO:
+        case PHDF5:
+        MPI_File_delete(fname, h5_io_info_g);
+        break;
+    }
     }
 }
 
@@ -2465,8 +2678,8 @@ do_cleanupfile(iotype iot, char *fname)
 gpfs_access_range(int handle, off_t start, off_t length, int is_write)
 {
     struct {
-	gpfsFcntlHeader_t hdr;
-	gpfsAccessRange_t access;
+    gpfsFcntlHeader_t hdr;
+    gpfsAccessRange_t access;
     } access_range;
 
     access_range.hdr.totalLength = sizeof(access_range);
@@ -2479,10 +2692,10 @@ gpfs_access_range(int handle, off_t start, off_t length, int is_write)
     access_range.access.isWrite = is_write;
 
     if (gpfs_fcntl(handle, &access_range) != 0) {
-	fprintf(stderr,
-		"gpfs_fcntl DS start directive failed. errno=%d errorOffset=%d\n",
-		errno, access_range.hdr.errorOffset);
-	exit(EXIT_FAILURE);
+    fprintf(stderr,
+        "gpfs_fcntl DS start directive failed. errno=%d errorOffset=%d\n",
+        errno, access_range.hdr.errorOffset);
+    exit(EXIT_FAILURE);
     }
 }
 
@@ -2514,8 +2727,8 @@ gpfs_access_range(int handle, off_t start, off_t length, int is_write)
 gpfs_free_range(int handle, off_t start, off_t length)
 {
     struct {
-	gpfsFcntlHeader_t hdr;
-	gpfsFreeRange_t range;
+    gpfsFcntlHeader_t hdr;
+    gpfsFreeRange_t range;
     } free_range;
 
     /* Issue the invalidate hint */
@@ -2528,10 +2741,10 @@ gpfs_free_range(int handle, off_t start, off_t length)
     free_range.range.length = length;
 
     if (gpfs_fcntl(handle, &free_range) != 0) {
-	fprintf(stderr,
-		"gpfs_fcntl free range failed for range %d:%d. errno=%d errorOffset=%d\n",
-		start, length, errno, free_range.hdr.errorOffset);
-	exit(EXIT_FAILURE);
+    fprintf(stderr,
+        "gpfs_fcntl free range failed for range %d:%d. errno=%d errorOffset=%d\n",
+        start, length, errno, free_range.hdr.errorOffset);
+    exit(EXIT_FAILURE);
     }
 }
 
@@ -2558,8 +2771,8 @@ gpfs_free_range(int handle, off_t start, off_t length)
 gpfs_clear_file_cache(int handle)
 {
     struct {
-	gpfsFcntlHeader_t hdr;
-	gpfsClearFileCache_t clear;
+    gpfsFcntlHeader_t hdr;
+    gpfsClearFileCache_t clear;
     } clear_cache;
 
     clear_cache.hdr.totalLength = sizeof(clear_cache);
@@ -2569,10 +2782,10 @@ gpfs_clear_file_cache(int handle)
     clear_cache.clear.structType = GPFS_CLEAR_FILE_CACHE;
 
     if (gpfs_fcntl(handle, &clear_cache) != 0) {
-	fprintf(stderr,
-		"gpfs_fcntl clear file cache directive failed. errno=%d errorOffset=%d\n",
-		errno, clear_cache.hdr.errorOffset);
-	exit(EXIT_FAILURE);
+    fprintf(stderr,
+        "gpfs_fcntl clear file cache directive failed. errno=%d errorOffset=%d\n",
+        errno, clear_cache.hdr.errorOffset);
+    exit(EXIT_FAILURE);
     }
 }
 
@@ -2604,8 +2817,8 @@ gpfs_clear_file_cache(int handle)
 gpfs_cancel_hints(int handle)
 {
     struct {
-	gpfsFcntlHeader_t hdr;
-	gpfsCancelHints_t cancel;
+    gpfsFcntlHeader_t hdr;
+    gpfsCancelHints_t cancel;
     } cancel_hints;
 
     cancel_hints.hdr.totalLength = sizeof(cancel_hints);
@@ -2615,10 +2828,10 @@ gpfs_cancel_hints(int handle)
     cancel_hints.cancel.structType = GPFS_CANCEL_HINTS;
 
     if (gpfs_fcntl(handle, &cancel_hints) != 0) {
-	fprintf(stderr,
-		"gpfs_fcntl cancel hints directive failed. errno=%d errorOffset=%d\n",
-		errno, cancel_hints.hdr.errorOffset);
-	exit(EXIT_FAILURE);
+    fprintf(stderr,
+        "gpfs_fcntl cancel hints directive failed. errno=%d errorOffset=%d\n",
+        errno, cancel_hints.hdr.errorOffset);
+    exit(EXIT_FAILURE);
     }
 }
 
@@ -2650,8 +2863,8 @@ gpfs_cancel_hints(int handle)
 gpfs_start_data_shipping(int handle, int num_insts)
 {
     struct {
-	gpfsFcntlHeader_t hdr;
-	gpfsDataShipStart_t start;
+    gpfsFcntlHeader_t hdr;
+    gpfsDataShipStart_t start;
     } ds_start;
 
     ds_start.hdr.totalLength = sizeof(ds_start);
@@ -2663,10 +2876,10 @@ gpfs_start_data_shipping(int handle, int num_insts)
     ds_start.start.reserved = 0;
 
     if (gpfs_fcntl(handle, &ds_start) != 0) {
-	fprintf(stderr,
-		"gpfs_fcntl DS start directive failed. errno=%d errorOffset=%d\n",
-		errno, ds_start.hdr.errorOffset);
-	exit(EXIT_FAILURE);
+    fprintf(stderr,
+        "gpfs_fcntl DS start directive failed. errno=%d errorOffset=%d\n",
+        errno, ds_start.hdr.errorOffset);
+    exit(EXIT_FAILURE);
     }
 }
 
@@ -2691,12 +2904,12 @@ gpfs_start_data_shipping(int handle, int num_insts)
  */
     static void
 gpfs_start_data_ship_map(int handle, int partition_size, int agent_count,
-	int *agent_node_num)
+    int *agent_node_num)
 {
     int i;
     struct {
-	gpfsFcntlHeader_t hdr;
-	gpfsDataShipMap_t map;
+    gpfsFcntlHeader_t hdr;
+    gpfsDataShipMap_t map;
     } ds_map;
 
     ds_map.hdr.totalLength = sizeof(ds_map);
@@ -2708,13 +2921,13 @@ gpfs_start_data_ship_map(int handle, int partition_size, int agent_count,
     ds_map.map.agentCount = agent_count;
 
     for (i = 0; i < agent_count; ++i)
-	ds_map.map.agentNodeNumber[i] = agent_node_num[i];
+    ds_map.map.agentNodeNumber[i] = agent_node_num[i];
 
     if (gpfs_fcntl(handle, &ds_map) != 0) {
-	fprintf(stderr,
-		"gpfs_fcntl DS map directive failed. errno=%d errorOffset=%d\n",
-		errno, ds_map.hdr.errorOffset);
-	exit(EXIT_FAILURE);
+    fprintf(stderr,
+        "gpfs_fcntl DS map directive failed. errno=%d errorOffset=%d\n",
+        errno, ds_map.hdr.errorOffset);
+    exit(EXIT_FAILURE);
     }
 }
 
@@ -2746,8 +2959,8 @@ gpfs_start_data_ship_map(int handle, int partition_size, int agent_count,
 gpfs_stop_data_shipping(int handle)
 {
     struct {
-	gpfsFcntlHeader_t hdr;
-	gpfsDataShipStop_t stop;
+    gpfsFcntlHeader_t hdr;
+    gpfsDataShipStop_t stop;
     } ds_stop;
 
     ds_stop.hdr.totalLength = sizeof(ds_stop);
@@ -2757,9 +2970,9 @@ gpfs_stop_data_shipping(int handle)
     ds_stop.stop.structType = GPFS_DATA_SHIP_STOP;
 
     if (gpfs_fcntl(handle, &ds_stop) != 0)
-	fprintf(stderr,
-		"gpfs_fcntl DS stop directive failed. errno=%d errorOffset=%d\n",
-		errno, ds_stop.hdr.errorOffset);
+    fprintf(stderr,
+        "gpfs_fcntl DS stop directive failed. errno=%d errorOffset=%d\n",
+        errno, ds_stop.hdr.errorOffset);
 }
 
 /*
@@ -2775,15 +2988,15 @@ gpfs_invalidate_file_cache(const char *filename)
 {
     int handle;
     struct {
-	gpfsFcntlHeader_t hdr;
-	gpfsClearFileCache_t inv;
+    gpfsFcntlHeader_t hdr;
+    gpfsClearFileCache_t inv;
     } inv_cache_hint;
 
     /* Open the file.  If the open fails, the file cannot be cached. */
     handle = open(filename, O_RDONLY, 0);
 
     if (handle == -1)
-	return;
+    return;
 
     /* Issue the invalidate hint */
     inv_cache_hint.hdr.totalLength = sizeof(inv_cache_hint);
@@ -2793,21 +3006,21 @@ gpfs_invalidate_file_cache(const char *filename)
     inv_cache_hint.inv.structType = GPFS_CLEAR_FILE_CACHE;
 
     if (gpfs_fcntl(handle, &inv_cache_hint) != 0) {
-	fprintf(stderr,
-		"gpfs_fcntl clear cache hint failed for file '%s'.",
-		filename);
-	fprintf(stderr, " errno=%d errorOffset=%d\n",
-		errno, inv_cache_hint.hdr.errorOffset);
-	exit(1);
+    fprintf(stderr,
+        "gpfs_fcntl clear cache hint failed for file '%s'.",
+        filename);
+    fprintf(stderr, " errno=%d errorOffset=%d\n",
+        errno, inv_cache_hint.hdr.errorOffset);
+    exit(1);
     }
 
     /* Close the file */
     if (close(handle) == -1) {
-	fprintf(stderr,
-		"could not close file '%s' after flushing file cache, ",
-		filename);
-	fprintf(stderr, "errno=%d\n", errno);
-	exit(1);
+    fprintf(stderr,
+        "could not close file '%s' after flushing file cache, ",
+        filename);
+    fprintf(stderr, "errno=%d\n", errno);
+    exit(1);
     }
 }
 
@@ -2819,7 +3032,7 @@ gpfs_invalidate_file_cache(const char *filename)
 
     static void
 gpfs_access_range(int UNUSED handle, off_t UNUSED start, off_t UNUSED length,
-	int UNUSED is_write)
+    int UNUSED is_write)
 {
     return;
 }
@@ -2856,7 +3069,7 @@ gpfs_stop_data_shipping(int UNUSED handle)
 
     static void
 gpfs_start_data_ship_map(int UNUSED handle, int UNUSED partition_size,
-	int UNUSED agent_count, int UNUSED *agent_node_num)
+    int UNUSED agent_count, int UNUSED *agent_node_num)
 {
     return;
 }
@@ -2876,7 +3089,7 @@ gpfs_invalidate_file_cache(const char UNUSED *filename)
  * pure time spent in MPI_File code.
  */
 int MPI_File_read_at(MPI_File fh, MPI_Offset offset, void *buf,
-	int count, MPI_Datatype datatype, MPI_Status *status)
+    int count, MPI_Datatype datatype, MPI_Status *status)
 {
     int err;
     set_time(timer_g, HDF5_MPI_READ, START);
@@ -2887,7 +3100,7 @@ int MPI_File_read_at(MPI_File fh, MPI_Offset offset, void *buf,
 
 
 int MPI_File_read_at_all(MPI_File fh, MPI_Offset offset, void *buf,
-	int count, MPI_Datatype datatype, MPI_Status *status)
+    int count, MPI_Datatype datatype, MPI_Status *status)
 {
     int err;
     set_time(timer_g, HDF5_MPI_READ, START);
@@ -2897,7 +3110,7 @@ int MPI_File_read_at_all(MPI_File fh, MPI_Offset offset, void *buf,
 }
 
 int MPI_File_write_at(MPI_File fh, MPI_Offset offset, void *buf,
-	int count, MPI_Datatype datatype, MPI_Status *status)
+    int count, MPI_Datatype datatype, MPI_Status *status)
 {
     int err;
     set_time(timer_g, HDF5_MPI_WRITE, START);
@@ -2907,7 +3120,7 @@ int MPI_File_write_at(MPI_File fh, MPI_Offset offset, void *buf,
 }
 
 int MPI_File_write_at_all(MPI_File fh, MPI_Offset offset, void *buf,
-	int count, MPI_Datatype datatype, MPI_Status *status)
+    int count, MPI_Datatype datatype, MPI_Status *status)
 {
     int err;
     set_time(timer_g, HDF5_MPI_WRITE, START);
@@ -2916,5 +3129,10 @@ int MPI_File_write_at_all(MPI_File fh, MPI_Offset offset, void *buf,
     return err;
 }
 
-#endif	/* TIME_MPI */
+#endif  /* TIME_MPI */
 #endif /* H5_HAVE_PARALLEL */
+
+
+
+
+