[svn-r5799] Purpose:

    New feature.

Description:
    Added MPI-posix VFL driver.  This driver uses MPI to coordinate actions, but
    performs I/O directly with posix sec(2) I/O functions.  This driver should
    _NOT_ be used if the file accessed is not on a parallel filesystem.

Platforms tested:
    FreeBSD 4.6 (sleipnir) w/parallel & IRIX64 6.5 (modi4) w/parallel

14 files changed, 1427 insertions, 167 deletions

diff --git a/src/H5D.c b/src/H5D.c
index d125bd5..e3fb8e1 100644
--- a/src/H5D.c
+++ b/src/H5D.c
@@ -30,10 +30,12 @@
 /*#define H5D_DEBUG*/
 
 /*
- * The MPIO driver is needed because there are kludges in this file and
- * places where we check for things that aren't handled by this driver.
+ * The MPIO & MPIPOSIX drivers are needed because there are kludges in this
+ * file and places where we check for things that aren't handled by these
+ * drivers.
  */
 #include "H5FDmpio.h"
+#include "H5FDmpiposix.h"
 
 #ifdef H5_HAVE_PARALLEL
 /* Remove this if H5R_DATASET_REGION is no longer used in this file */
@@ -1541,8 +1543,8 @@ H5D_create(H5G_entry_t *loc, const char *name, const H5T_t *type,
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "unable to locate insertion point");
 
 #ifdef H5_HAVE_PARALLEL
-    /* If MPIO is used, no filter support yet. */
-    if(IS_H5FD_MPIO(f) && dcpl_pline.nfilters > 0) 
+    /* If MPIO or MPIPOSIX is used, no filter support yet. */
+    if((IS_H5FD_MPIO(f) || IS_H5FD_MPIPOSIX(f)) && dcpl_pline.nfilters > 0) 
         HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, NULL, "Parallel I/O does not support filters yet");
 #endif /*H5_HAVE_PARALLEL*/
    
@@ -2018,8 +2020,8 @@ H5D_open_oid(H5G_entry_t *ent)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTSET, NULL, "can't set pipeline");
 
 #ifdef H5_HAVE_PARALLEL
-    /* If MPIO is used, no filter support yet. */
-    if(IS_H5FD_MPIO(dataset->ent.file) && pline.nfilters > 0)
+    /* If MPIO or MPIPOSIX is used, no filter support yet. */
+    if((IS_H5FD_MPIO(dataset->ent.file) || IS_H5FD_MPIPOSIX(dataset->ent.file)) && pline.nfilters > 0)
         HGOTO_ERROR (H5E_DATASET, H5E_UNSUPPORTED, NULL, "Parallel IO does not support filters yet");
 #endif /*H5_HAVE_PARALLEL*/
     
@@ -2224,7 +2226,7 @@ H5D_read(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
     H5S_t	*free_this_space=NULL;  /*data space to free	*/
 #ifdef H5_HAVE_PARALLEL
     H5FD_mpio_dxpl_t *dx = NULL;
-    H5FD_mpio_xfer_t xfer_mode;		/*xfer_mode for this request */
+    H5FD_mpio_xfer_t xfer_mode=H5FD_MPIO_INDEPENDENT;	/*xfer_mode for this request */
     hbool_t	xfer_mode_changed=0;	/*xfer_mode needs restore */
     hbool_t	doing_mpio=0;		/*This is an MPIO access */
 #endif /*H5_HAVE_PARALLEL*/
@@ -2280,10 +2282,10 @@ H5D_read(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
 	    xfer_mode = dx->xfer_mode;
         }
     } /* end if */
-    /* Collective access is not permissible without the MPIO driver */
+    /* Collective access is not permissible without the MPIO or MPIPOSIX driver */
     if (doing_mpio && xfer_mode==H5FD_MPIO_COLLECTIVE &&
-            !(IS_H5FD_MPIO(dataset->ent.file)))
-        HGOTO_ERROR (H5E_DATASET, H5E_UNSUPPORTED, FAIL, "collective access for MPIO driver only");
+            !(IS_H5FD_MPIO(dataset->ent.file) || IS_H5FD_MPIPOSIX(dataset->ent.file)))
+        HGOTO_ERROR (H5E_DATASET, H5E_UNSUPPORTED, FAIL, "collective access for MPIO & MPIPOSIX drivers only");
 
     /* Set the "parallel I/O possible" flag, for H5S_find() */
     if (H5S_mpi_opt_types_g && IS_H5FD_MPIO(dataset->ent.file)) {
@@ -2640,7 +2642,7 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
     H5S_t	*free_this_space=NULL;	/*data space to free	*/
 #ifdef H5_HAVE_PARALLEL
     H5FD_mpio_dxpl_t	*dx = NULL;
-    H5FD_mpio_xfer_t	xfer_mode;	/*xfer_mode for this request */
+    H5FD_mpio_xfer_t xfer_mode=H5FD_MPIO_INDEPENDENT;	/*xfer_mode for this request */
     hbool_t	xfer_mode_changed=0;	/*xfer_mode needs restore */
     hbool_t	doing_mpio=0;		/*This is an MPIO access */
 #endif /*H5_HAVE_PARALLEL*/
@@ -2677,17 +2679,17 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset creation property list");
 
 #ifdef H5_HAVE_PARALLEL
-    /* If MPIO is used, no VL datatype support yet. */
+    /* If MPIO or MPIPOSIX is used, no VL datatype support yet. */
     /* This is because they use the global heap in the file and we don't */
     /* support parallel access of that yet */
-    if (IS_H5FD_MPIO(dataset->ent.file) && H5T_get_class(mem_type)==H5T_VLEN)
+    if ( (IS_H5FD_MPIO(dataset->ent.file) || IS_H5FD_MPIPOSIX(dataset->ent.file)) && H5T_get_class(mem_type)==H5T_VLEN)
         HGOTO_ERROR (H5E_DATASET, H5E_UNSUPPORTED, FAIL, "Parallel IO does not support writing VL datatypes yet");
 #endif /*H5_HAVE_PARALLEL*/
 #ifdef H5_HAVE_PARALLEL
-    /* If MPIO is used, no dataset region reference support yet. */
+    /* If MPIO or MPIPOSIX is used, no dataset region reference datatype support yet. */
     /* This is because they use the global heap in the file and we don't */
     /* support parallel access of that yet */
-    if (IS_H5FD_MPIO(dataset->ent.file) &&
+    if ((IS_H5FD_MPIO(dataset->ent.file) || IS_H5FD_MPIPOSIX(dataset->ent.file)) &&
             H5T_get_class(mem_type)==H5T_REFERENCE &&
             H5T_get_ref_type(mem_type)==H5R_DATASET_REGION)
         HGOTO_ERROR (H5E_DATASET, H5E_UNSUPPORTED, FAIL, "Parallel IO does not support writing region reference datatypes yet");
@@ -2715,9 +2717,9 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
 	    xfer_mode = dx->xfer_mode;
         }
     } /* end if */
-    /* Collective access is not permissible without the MPIO driver */
+    /* Collective access is not permissible without the MPIO or MPIPOSIX driver */
     if (doing_mpio && xfer_mode==H5FD_MPIO_COLLECTIVE &&
-            !(IS_H5FD_MPIO(dataset->ent.file)))
+            !(IS_H5FD_MPIO(dataset->ent.file) || IS_H5FD_MPIPOSIX(dataset->ent.file)))
         HGOTO_ERROR (H5E_DATASET, H5E_UNSUPPORTED, FAIL, "collective access for MPIO driver only");
 
     /* Set the "parallel I/O possible" flag, for H5S_find() */
@@ -3269,7 +3271,7 @@ H5D_init_storage(H5D_t *dset, const H5S_t *space)
              * If the dataset is accessed via parallel I/O, allocate file space
              * for all chunks now and initialize each chunk with the fill value.
              */
-            if (IS_H5FD_MPIO(dset->ent.file)) {
+            if (IS_H5FD_MPIO(dset->ent.file) || IS_H5FD_MPIPOSIX(dset->ent.file)) {
                 /* We only handle simple data spaces so far */
                 int		ndims;
                 hsize_t		dim[H5O_LAYOUT_NDIMS];
diff --git a/src/H5Distore.c b/src/H5Distore.c
index a44ce5a..a9f7f56 100644
--- a/src/H5Distore.c
+++ b/src/H5Distore.c
@@ -45,8 +45,9 @@
 #include "H5Sprivate.h"         /* Dataspaces */
 #include "H5Vprivate.h"
 
-/* MPIO driver needed for special checks */
+/* MPIO & MPIPOSIX drivers needed for special checks */
 #include "H5FDmpio.h"
+#include "H5FDmpiposix.h"
 
 /*
  * Feature: If this constant is defined then every cache preemption and load
@@ -1781,12 +1782,12 @@ H5F_istore_read(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
 
 #ifdef H5_HAVE_PARALLEL
         /*
-         * If MPIO is used and file can be written to, we must bypass the
+         * If MPIO or MPIPOSIX is used and file can be written to, we must bypass the
          * chunk-cache scheme because other MPI processes could be writing to
          * other elements in the same chunk.
          * Do a direct write-through of only the elements requested.
          */
-            || (IS_H5FD_MPIO(f) && (H5F_ACC_RDWR & f->shared->flags))
+            || ((IS_H5FD_MPIO(f) ||IS_H5FD_MPIPOSIX(f)) && (H5F_ACC_RDWR & f->shared->flags))
 #endif /* H5_HAVE_PARALLEL */
             ) {
             H5O_layout_t	l;	/* temporary layout */
@@ -1965,11 +1966,11 @@ H5F_istore_write(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
 
 #ifdef H5_HAVE_PARALLEL
         /*
-         * If MPIO is used, must bypass the chunk-cache scheme because other
+         * If MPIO or MPIPOSIX is used, must bypass the chunk-cache scheme because other
          * MPI processes could be writing to other elements in the same chunk.
          * Do a direct write-through of only the elements requested.
          */
-            || (IS_H5FD_MPIO(f) && (H5F_ACC_RDWR & f->shared->flags))
+            || ((IS_H5FD_MPIO(f) ||IS_H5FD_MPIPOSIX(f)) && (H5F_ACC_RDWR & f->shared->flags))
 #endif /* H5_HAVE_PARALLEL */
             ) {
             H5O_layout_t	l;	/* temporary layout */
@@ -2416,10 +2417,22 @@ H5F_istore_allocate(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
     } /* end if */
 
     /* Retrieve up MPI parameters */
-    if ((mpi_rank=H5FD_mpio_mpi_rank(f->shared->lf))<0)
-        HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "Can't retrieve MPI rank");
-    if ((mpi_size=H5FD_mpio_mpi_size(f->shared->lf))<0)
-        HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "Can't retrieve MPI size");
+    if(IS_H5FD_MPIO(f)) {
+        if ((mpi_rank=H5FD_mpio_mpi_rank(f->shared->lf))<0)
+            HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "Can't retrieve MPI rank");
+        if ((mpi_size=H5FD_mpio_mpi_size(f->shared->lf))<0)
+            HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "Can't retrieve MPI size");
+    } /* end if */
+    else {
+        /* Sanity Check */
+        assert(IS_H5FD_MPIPOSIX(f));
+
+        /* Get the MPI rank & size */
+        if ((mpi_rank=H5FD_mpiposix_mpi_rank(f->shared->lf))<0)
+            HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "Can't retrieve MPI rank");
+        if ((mpi_size=H5FD_mpiposix_mpi_size(f->shared->lf))<0)
+            HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "Can't retrieve MPI size");
+    } /* end else */
 
     /* Loop over all chunks */
     carry=0;
@@ -2469,8 +2482,17 @@ H5F_istore_allocate(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
          * still writing out chunks and other processes race ahead to read
          * them in, getting bogus data.
          */
-        if (MPI_Barrier(H5FD_mpio_communicator(f->shared->lf)))
-            HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "MPI_Barrier failed");
+        if(IS_H5FD_MPIO(f)) {
+            if (MPI_Barrier(H5FD_mpio_communicator(f->shared->lf)))
+                HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "MPI_Barrier failed");
+        } /* end if */
+        else {
+            /* Sanity Check */
+            assert(IS_H5FD_MPIPOSIX(f));
+
+            if (MPI_Barrier(H5FD_mpiposix_communicator(f->shared->lf)))
+                HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "MPI_Barrier failed");
+        } /* end else */
     } /* end if */
 
 done:
diff --git a/src/H5Dseq.c b/src/H5Dseq.c
index 0a4da84..8f988ff 100644
--- a/src/H5Dseq.c
+++ b/src/H5Dseq.c
@@ -26,8 +26,9 @@
 #include "H5Pprivate.h"
 #include "H5Vprivate.h"
 
-/* MPIO driver functions are needed for some special checks */
+/* MPIO & MPIPOSIX driver functions are needed for some special checks */
 #include "H5FDmpio.h"
+#include "H5FDmpiposix.h"
 
 /* Interface initialization */
 #define PABLO_MASK	H5Fseq_mask
@@ -182,27 +183,29 @@ H5F_seq_readv(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
 
 #ifdef H5_HAVE_PARALLEL
     {
-	/* Get the transfer mode */
 	H5FD_mpio_dxpl_t *dx;
         hid_t driver_id;            /* VFL driver ID */
 
-        /* Get the plist structure */
-        if(NULL == (plist = H5I_object(dxpl_id)))
-            HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
-
-        /* Get the driver ID */
-        if(H5P_get(plist, H5D_XFER_VFL_ID_NAME, &driver_id)<0)
-            HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver ID");
-
-        /* Check if we are using the MPIO driver */
-        if(H5FD_MPIO==driver_id) {
-            /* Get the driver information */
-            if(H5P_get(plist, H5D_XFER_VFL_INFO_NAME, &dx)<0)
-                HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver info");
-
-            /* Check if we are not using independent I/O */
-            if(H5FD_MPIO_INDEPENDENT!=dx->xfer_mode)
-                xfer_mode = dx->xfer_mode;
+	/* Get the transfer mode for MPIO transfers */
+        if(IS_H5FD_MPIO(f)) {
+            /* Get the plist structure */
+            if(NULL == (plist = H5I_object(dxpl_id)))
+                HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
+
+            /* Get the driver ID */
+            if(H5P_get(plist, H5D_XFER_VFL_ID_NAME, &driver_id)<0)
+                HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver ID");
+
+            /* Check if we are using the MPIO driver (for the DXPL) */
+            if(H5FD_MPIO==driver_id) {
+                /* Get the driver information */
+                if(H5P_get(plist, H5D_XFER_VFL_INFO_NAME, &dx)<0)
+                    HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver info");
+
+                /* Check if we are not using independent I/O */
+                if(H5FD_MPIO_INDEPENDENT!=dx->xfer_mode)
+                    xfer_mode = dx->xfer_mode;
+            } /* end if */
         } /* end if */
     }
 
@@ -564,27 +567,29 @@ H5F_seq_writev(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
 
 #ifdef H5_HAVE_PARALLEL
     {
-	/* Get the transfer mode */
 	H5FD_mpio_dxpl_t *dx;
         hid_t driver_id;            /* VFL driver ID */
 
-        /* Get the plist structure */
-        if(NULL == (plist = H5I_object(dxpl_id)))
-            HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
-
-        /* Get the driver ID */
-        if(H5P_get(plist, H5D_XFER_VFL_ID_NAME, &driver_id)<0)
-            HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver ID");
-
-        /* Check if we are using the MPIO driver */
-        if(H5FD_MPIO==driver_id) {
-            /* Get the driver information */
-            if(H5P_get(plist, H5D_XFER_VFL_INFO_NAME, &dx)<0)
-                HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver info");
-
-            /* Check if we are not using independent I/O */
-            if(H5FD_MPIO_INDEPENDENT!=dx->xfer_mode)
-                xfer_mode = dx->xfer_mode;
+	/* Get the transfer mode for MPIO transfers */
+        if(IS_H5FD_MPIO(f)) {
+            /* Get the plist structure */
+            if(NULL == (plist = H5I_object(dxpl_id)))
+                HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
+
+            /* Get the driver ID */
+            if(H5P_get(plist, H5D_XFER_VFL_ID_NAME, &driver_id)<0)
+                HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver ID");
+
+            /* Check if we are using the MPIO driver (for the DXPL) */
+            if(H5FD_MPIO==driver_id) {
+                /* Get the driver information */
+                if(H5P_get(plist, H5D_XFER_VFL_INFO_NAME, &dx)<0)
+                    HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver info");
+
+                /* Check if we are not using independent I/O */
+                if(H5FD_MPIO_INDEPENDENT!=dx->xfer_mode)
+                    xfer_mode = dx->xfer_mode;
+            } /* end if */
         } /* end if */
     }
 
diff --git a/src/H5F.c b/src/H5F.c
index 1e6f3a7..68f82cf 100644
--- a/src/H5F.c
+++ b/src/H5F.c
@@ -22,6 +22,7 @@
 #include "H5FDcore.h"		/*temporary in-memory files		  */
 #include "H5FDfamily.h"		/*family of files			  */
 #include "H5FDmpio.h"		/*MPI-2 I/O				  */
+#include "H5FDmpiposix.h"	/*MPI-2 & posix I/O			  */
 #include "H5FDgass.h"           /*GASS I/O                                */
 #include "H5FDstream.h"         /*in-memory files streamed via sockets    */
 #include "H5FDsrb.h"            /*SRB I/O                                 */
@@ -215,7 +216,7 @@ H5F_init_interface(void)
         /* Allow MPI buf-and-file-type optimizations? */
         const char *s = HDgetenv ("HDF5_MPI_1_METAWRITE");
         if (s && HDisdigit(*s)) {
-            H5_mpi_1_metawrite_g = (int)HDstrtol (s, NULL, 0);
+            H5_mpiposix_1_metawrite_g = H5_mpi_1_metawrite_g = (int)HDstrtol (s, NULL, 0);
         }
     }
 #endif /* H5_HAVE_PARALLEL */
@@ -304,6 +305,7 @@ H5F_init_interface(void)
 	if ((status=H5FD_MULTI)<0) goto end_registration;
 #ifdef H5_HAVE_PARALLEL
 	if ((status=H5FD_MPIO)<0) goto end_registration;
+	if ((status=H5FD_MPIPOSIX)<0) goto end_registration;
 #endif /* H5_HAVE_PARALLEL */
 #ifdef H5_HAVE_STREAM
 	if ((status=H5FD_STREAM)<0) goto end_registration;
@@ -2571,7 +2573,6 @@ H5F_close(H5F_t *f)
 {
     H5F_close_degree_t	fc_degree;      /* What action to take when closing the last file ID for a file */
     hid_t		*oid_list;      /* List of IDs still open */
-    unsigned		oid_count;      /* Number of IDs still open */
     unsigned		i;              /* Local index variable */
     unsigned	        closing=0;      /* Indicate that the file will be closed */
     herr_t	        ret_value = SUCCEED;    /* Return value */
diff --git a/src/H5FD.c b/src/H5FD.c
index d905fdf..fb25da8 100644
--- a/src/H5FD.c
+++ b/src/H5FD.c
@@ -1611,7 +1611,7 @@ H5FD_real_alloc(H5FD_t *file, H5FD_mem_t type, hsize_t size)
         }
     } else {
 	hsize_t	wasted;
-        haddr_t oldeoa;
+        haddr_t oldeoa=0;
 	haddr_t eoa = (file->cls->get_eoa)(file);
 
 #ifdef H5F_DEBUG
diff --git a/src/H5FDmpio.c b/src/H5FDmpio.c
index 7f36862..df4b95c 100644
--- a/src/H5FDmpio.c
+++ b/src/H5FDmpio.c
@@ -72,9 +72,9 @@ static haddr_t H5FD_mpio_get_eoa(H5FD_t *_file);
 static herr_t H5FD_mpio_set_eoa(H5FD_t *_file, haddr_t addr);
 static haddr_t H5FD_mpio_get_eof(H5FD_t *_file);
 static herr_t H5FD_mpio_read(H5FD_t *_file, H5FD_mem_t type, hid_t fapl_id, haddr_t addr,
-			     size_t size, void *buf);
+            size_t size, void *buf);
 static herr_t H5FD_mpio_write(H5FD_t *_file, H5FD_mem_t type, hid_t fapl_id, haddr_t addr,
-			      size_t size, const void *buf);
+            size_t size, const void *buf);
 static herr_t H5FD_mpio_flush(H5FD_t *_file, unsigned closing);
 
 /* MPIO-specific file access properties */
diff --git a/src/H5FDmpiposix.c b/src/H5FDmpiposix.c
new file mode 100644
index 0000000..82533d0
--- /dev/null
+++ b/src/H5FDmpiposix.c
@@ -0,0 +1,1135 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by the Board of Trustees of the University of Illinois.         *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the files COPYING and Copyright.html.  COPYING can be found at the root   *
+ * of the source code distribution tree; Copyright.html can be found at the  *
+ * root level of an installed copy of the electronic HDF5 document set and   *
+ * is linked from the top-level documents page.  It can also be found at     *
+ * http://hdf.ncsa.uiuc.edu/HDF5/doc/Copyright.html.  If you do not have     *
+ * access to either file, you may request a copy from hdfhelp@ncsa.uiuc.edu. *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/*
+ * Programmer:  Quincey Koziol <koziol@ncsa.uiuc.ed>
+ *              Thursday, July 11, 2002
+ *
+ * Purpose:	This is a "combination" MPI-2 and posix I/O driver.
+ *              It uses MPI for coodinating the actions of several processes
+ *              and posix I/O calls to do the actual I/O to the disk.
+ *
+ *              This driver was derived from the H5FDmpio.c driver and may
+ *              share bugs/quirks/etc.
+ *
+ * Limitations:
+ *              There is no "collective" I/O mode with this driver.
+ *
+ *              This will almost certainly _not_ work correctly for files
+ *              accessed on distributed parallel systems with the file located
+ *              on a non-parallel filesystem.
+ *
+ */
+#include "H5private.h"		/*library functions			*/
+#include "H5Eprivate.h"		/*error handling			*/
+#include "H5Fprivate.h"		/*files					*/
+#include "H5FDprivate.h"	/*file driver			        */
+#include "H5FDmpiposix.h"       /* MPI/posix I/O file driver            */
+#include "H5Iprivate.h"		/* IDs			  		*/
+#include "H5MMprivate.h"        /*memory allocation                     */
+#include "H5Pprivate.h"		/*property lists			*/
+
+/*
+ * The driver identification number, initialized at runtime if H5_HAVE_PARALLEL
+ * is defined. This allows applications to still have the H5FD_MPIPOSIX
+ * "constants" in their source code (it also makes this file strictly ANSI
+ * compliant when H5_HAVE_PARALLEL isn't defined)
+ */
+static hid_t H5FD_MPIPOSIX_g = 0;
+
+#ifdef H5_HAVE_PARALLEL
+
+/* File operations */
+#define OP_UNKNOWN	0
+#define OP_READ		1
+#define OP_WRITE	2
+
+/*
+ * The description of a file belonging to this driver.
+ * The EOF value
+ * is only used just after the file is opened in order for the library to
+ * determine whether the file is empty, truncated, or okay. The MPIPOSIX driver
+ * doesn't bother to keep it updated since it's an expensive operation.
+ */
+typedef struct H5FD_mpiposix_t {
+    H5FD_t	pub;		/*public stuff, must be first		*/
+    int		fd;		/*the unix file handle		        */
+    MPI_Comm	comm;		/*communicator				*/
+    int         mpi_rank;       /* This process's rank                  */
+    int         mpi_size;       /* Total number of processes            */
+    int         mpi_round;      /* Current round robin process (for metadata I/O) */
+    haddr_t	eof;		/*end-of-file marker			*/
+    haddr_t	eoa;		/*end-of-address marker			*/
+    haddr_t	last_eoa;	/* Last known end-of-address marker	*/
+    haddr_t	pos;		/* Current file I/O position	        */
+    int		op;		/* Last file I/O operation		*/
+#ifndef WIN32
+    /*
+     * On most systems the combination of device and i-node number uniquely
+     * identify a file.
+     */
+    dev_t	device;		/*file device number		*/
+    ino_t	inode;		/*file i-node number		*/
+#else
+    /*
+     * On WIN32 the low-order word of a unique identifier associated with the
+     * file and the volume serial number uniquely identify a file. This number
+     * (which, both? -rpm) may change when the system is restarted or when the
+     * file is opened. After a process opens a file, the identifier is
+     * constant until the file is closed. An application can use this
+     * identifier and the volume serial number to determine whether two
+     * handles refer to the same file.
+     */
+    int fileindexlo;
+    int fileindexhi;
+#endif
+} H5FD_mpiposix_t;
+
+/*
+ * This driver supports systems that have the lseek64() function by defining
+ * some macros here so we don't have to have conditional compilations later
+ * throughout the code.
+ *
+ * file_offset_t:	The datatype for file offsets, the second argument of
+ *			the lseek() or lseek64() call.
+ *
+ * file_seek:		The function which adjusts the current file position,
+ *			either lseek() or lseek64().
+ */
+/* adding for windows NT file system support. */
+/* pvn: added __MWERKS__ support. */
+
+#ifdef H5_HAVE_LSEEK64
+#   define file_offset_t	off64_t
+#   define file_seek		lseek64
+#   define file_truncate	ftruncate64
+#elif defined (WIN32) && !defined(__MWERKS__)
+# /*MSVC*/
+#   define file_offset_t __int64
+#   define file_seek _lseeki64
+#   define file_truncate	_ftruncatei64
+#else
+#   define file_offset_t	off_t
+#   define file_seek		HDlseek
+#   define file_truncate	HDftruncate
+#endif
+
+/*
+ * These macros check for overflow of various quantities.  These macros
+ * assume that file_offset_t is signed and haddr_t and size_t are unsigned.
+ * 
+ * ADDR_OVERFLOW:	Checks whether a file address of type `haddr_t'
+ *			is too large to be represented by the second argument
+ *			of the file seek function.
+ *
+ * SIZE_OVERFLOW:	Checks whether a buffer size of type `hsize_t' is too
+ *			large to be represented by the `size_t' type.
+ *
+ * REGION_OVERFLOW:	Checks whether an address and size pair describe data
+ *			which can be addressed entirely by the second
+ *			argument of the file seek function.
+ */
+#define MAXADDR (((haddr_t)1<<(8*sizeof(file_offset_t)-1))-1)
+#define ADDR_OVERFLOW(A)	(HADDR_UNDEF==(A) ||			      \
+				 ((A) & ~(haddr_t)MAXADDR))
+#define SIZE_OVERFLOW(Z)	((Z) & ~(hsize_t)MAXADDR)
+#define REGION_OVERFLOW(A,Z)	(ADDR_OVERFLOW(A) || SIZE_OVERFLOW(Z) ||      \
+				 sizeof(file_offset_t)<sizeof(size_t) ||      \
+                                 HADDR_UNDEF==(A)+(Z) ||		      \
+				 (file_offset_t)((A)+(Z))<(file_offset_t)(A))
+
+/* Callbacks */
+static void *H5FD_mpiposix_fapl_get(H5FD_t *_file);
+static H5FD_t *H5FD_mpiposix_open(const char *name, unsigned flags, hid_t fapl_id,
+			      haddr_t maxaddr);
+static herr_t H5FD_mpiposix_close(H5FD_t *_file);
+static int H5FD_mpiposix_cmp(const H5FD_t *_f1, const H5FD_t *_f2);
+static herr_t H5FD_mpiposix_query(const H5FD_t *_f1, unsigned long *flags);
+static haddr_t H5FD_mpiposix_get_eoa(H5FD_t *_file);
+static herr_t H5FD_mpiposix_set_eoa(H5FD_t *_file, haddr_t addr);
+static haddr_t H5FD_mpiposix_get_eof(H5FD_t *_file);
+static herr_t H5FD_mpiposix_read(H5FD_t *_file, H5FD_mem_t type, hid_t fapl_id, haddr_t addr,
+        size_t size, void *buf);
+static herr_t H5FD_mpiposix_write(H5FD_t *_file, H5FD_mem_t type, hid_t fapl_id, haddr_t addr,
+        size_t size, const void *buf);
+static herr_t H5FD_mpiposix_flush(H5FD_t *_file, unsigned closing);
+
+/* MPIPOSIX-specific file access properties */
+typedef struct H5FD_mpiposix_fapl_t {
+    MPI_Comm		comm;		/*communicator			*/
+} H5FD_mpiposix_fapl_t;
+
+/* The MPIPOSIX file driver information */
+static const H5FD_class_t H5FD_mpiposix_g = {
+    "mpiposix",					/*name			*/
+    MAXADDR,					/*maxaddr		*/
+    H5F_CLOSE_SEMI,				/* fc_degree		*/
+    NULL,					/*sb_size		*/
+    NULL,					/*sb_encode		*/
+    NULL,					/*sb_decode		*/
+    sizeof(H5FD_mpiposix_fapl_t),		/*fapl_size		*/
+    H5FD_mpiposix_fapl_get,			/*fapl_get		*/
+    NULL,					/*fapl_copy		*/
+    NULL, 					/*fapl_free		*/
+    0,						/*dxpl_size		*/
+    NULL,					/*dxpl_copy		*/
+    NULL,					/*dxpl_free		*/
+    H5FD_mpiposix_open,				/*open			*/
+    H5FD_mpiposix_close,			/*close			*/
+    H5FD_mpiposix_cmp,			        /*cmp			*/
+    H5FD_mpiposix_query,		        /*query			*/
+    NULL,					/*alloc			*/
+    NULL,					/*free			*/
+    H5FD_mpiposix_get_eoa,			/*get_eoa		*/
+    H5FD_mpiposix_set_eoa, 			/*set_eoa		*/
+    H5FD_mpiposix_get_eof,			/*get_eof		*/
+    H5FD_mpiposix_read,				/*read			*/
+    H5FD_mpiposix_write,			/*write			*/
+    H5FD_mpiposix_flush,			/*flush			*/
+    H5FD_FLMAP_SINGLE,				/*fl_map		*/
+};
+
+/* Global var to allow elimination of redundant metadata writes
+ * to be controlled by the value of an environment variable. */
+/* Use the elimination by default unless this is the Intel Red machine */
+#ifndef __PUMAGON__
+hbool_t	H5_mpiposix_1_metawrite_g = TRUE;
+#else
+hbool_t	H5_mpiposix_1_metawrite_g = FALSE;
+#endif
+
+/* Interface initialization */
+#define PABLO_MASK	H5FD_mpiposix_mask
+#define INTERFACE_INIT	H5FD_mpiposix_init
+static int interface_initialize_g = 0;
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FD_mpiposix_init
+ *
+ * Purpose:	Initialize this driver by registering the driver with the
+ *		library.
+ *
+ * Return:	Success:	The driver ID for the mpiposix driver.
+ *
+ *		Failure:	Negative.
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5FD_mpiposix_init(void)
+{
+    FUNC_ENTER_NOAPI(H5FD_mpiposix_init, FAIL);
+
+    if (H5I_VFL!=H5Iget_type(H5FD_MPIPOSIX_g))
+        H5FD_MPIPOSIX_g = H5FDregister(&H5FD_mpiposix_g);
+
+    FUNC_LEAVE(H5FD_MPIPOSIX_g);
+} /* end H5FD_mpiposix_init() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5Pset_fapl_mpiposix
+ *
+ * Purpose:	Store the user supplied MPI communicator COMM in
+ *		the file access property list FAPL_ID which can then be used
+ *		to create and/or open the file.  This function is available
+ *		only in the parallel HDF5 library and is not collective.
+ *
+ *		COMM is the MPI communicator to be used for file open as
+ *		defined in MPI_FILE_OPEN of MPI-2. This function does not
+ *		make a duplicated communicator. Any modification to COMM
+ *		after this function call returns may have undetermined effect
+ *		on the access property list. Users should not modify the
+ *		communicator while it is defined in a property list.
+ *
+ * Return:	Success:	Non-negative
+ * 		Failure:	Negative
+ *
+ * Programmer:	Quincey Koziol
+ *		Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pset_fapl_mpiposix(hid_t fapl_id, MPI_Comm comm)
+{
+    H5FD_mpiposix_fapl_t	fa;
+    H5P_genplist_t *plist;      /* Property list pointer */
+    herr_t ret_value=FAIL;
+    
+    FUNC_ENTER_API(H5Pset_fapl_mpiposix, FAIL);
+    H5TRACE2("e","iMc",fapl_id,comm);
+
+    /* Check arguments */
+    if(TRUE!=H5P_isa_class(fapl_id,H5P_FILE_ACCESS) || NULL == (plist = H5I_object(fapl_id)))
+        HRETURN_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a file access list");
+#ifdef LATER
+#warning "We need to verify that COMM contains sensible information."
+#endif
+
+    /* Initialize driver specific properties */
+    fa.comm = comm;
+
+    ret_value= H5P_set_driver(plist, H5FD_MPIPOSIX, &fa);
+
+    FUNC_LEAVE(ret_value);
+} /* end H5Pset_fapl_mpiposix() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5Pget_fapl_mpiposix
+ *
+ * Purpose:	If the file access property list is set to the H5FD_MPIPOSIX
+ *		driver then this function returns the MPI communicator and
+ *		information through the COMM pointer.
+ *
+ * Return:	Success:	Non-negative with the communicator and
+ *				information returned through the COMM 
+ *				argument if non-null. This piece of
+ *				information is copied and is therefore
+ *				valid only until the file access property
+ *				list is modified or closed.
+ *
+ * 		Failure:	Negative
+ *
+ * Programmer:	Quincey Koziol
+ *		Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5Pget_fapl_mpiposix(hid_t fapl_id, MPI_Comm *comm/*out*/)
+{
+    H5FD_mpiposix_fapl_t	*fa;
+    H5P_genplist_t *plist;      /* Property list pointer */
+    
+    FUNC_ENTER_API(H5Pget_fapl_mpiposix, FAIL);
+    H5TRACE2("e","ix",fapl_id,comm);
+
+    if(TRUE!=H5P_isa_class(fapl_id,H5P_FILE_ACCESS) || NULL == (plist = H5I_object(fapl_id)))
+        HRETURN_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a file access list");
+    if (H5FD_MPIPOSIX!=H5P_get_driver(plist))
+        HRETURN_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "incorrect VFL driver");
+    if (NULL==(fa=H5P_get_driver_info(plist)))
+        HRETURN_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "bad VFL driver info");
+
+    /* Get MPI Communicator */
+    if (comm)
+        *comm = fa->comm;
+
+    FUNC_LEAVE(SUCCEED);
+} /* end H5Pget_fapl_mpiposix() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FD_mpiposix_communicator
+ *
+ * Purpose:	Returns the MPI communicator for the file.
+ *
+ * Return:	Success:	The communicator
+ *
+ *		Failure:	NULL
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+MPI_Comm
+H5FD_mpiposix_communicator(H5FD_t *_file)
+{
+    H5FD_mpiposix_t *file = (H5FD_mpiposix_t*)_file;
+
+    FUNC_ENTER_NOAPI(H5FD_mpiposix_communicator, MPI_COMM_NULL);
+
+    assert(file);
+    assert(H5FD_MPIPOSIX==file->pub.driver_id);
+
+    FUNC_LEAVE(file->comm);
+} /* end H5FD_mpi_posix_communicator() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FD_mpiposix_mpi_rank
+ *
+ * Purpose:	Returns the MPI rank for a process
+ *
+ * Return:	Success: non-negative
+ *		Failure: negative
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+int
+H5FD_mpiposix_mpi_rank(H5FD_t *_file)
+{
+    H5FD_mpiposix_t *file = (H5FD_mpiposix_t*)_file;
+
+    FUNC_ENTER_NOAPI(H5FD_mpiposix_mpi_rank, FAIL);
+
+    assert(file);
+    assert(H5FD_MPIPOSIX==file->pub.driver_id);
+
+    FUNC_LEAVE(file->mpi_rank);
+} /* end H5FD_mpiposix_mpi_rank() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FD_mpiposix_mpi_size
+ *
+ * Purpose:	Returns the number of MPI processes
+ *
+ * Return:	Success: non-negative
+ *		Failure: negative
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+int
+H5FD_mpiposix_mpi_size(H5FD_t *_file)
+{
+    H5FD_mpiposix_t *file = (H5FD_mpiposix_t*)_file;
+
+    FUNC_ENTER_NOAPI(H5FD_mpiposix_mpi_rank, FAIL);
+
+    assert(file);
+    assert(H5FD_MPIPOSIX==file->pub.driver_id);
+
+    FUNC_LEAVE(file->mpi_size);
+} /* end H5FD_mpiposix_mpi_size() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FD_mpiposix_fapl_get
+ *
+ * Purpose:	Returns a file access property list which could be used to
+ *		create another file the same as this one.
+ *
+ * Return:	Success:	Ptr to new file access property list with all
+ *				fields copied from the file pointer.
+ *
+ *		Failure:	NULL
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static void *
+H5FD_mpiposix_fapl_get(H5FD_t *_file)
+{
+    H5FD_mpiposix_t	*file = (H5FD_mpiposix_t*)_file;
+    H5FD_mpiposix_fapl_t *fa = NULL;
+
+    FUNC_ENTER_NOAPI(H5FD_mpiposix_fapl_get, NULL);
+
+    assert(file);
+    assert(H5FD_MPIPOSIX==file->pub.driver_id);
+
+    if (NULL==(fa=H5MM_calloc(sizeof(H5FD_mpiposix_fapl_t))))
+        HRETURN_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
+
+    /* These should be copied. --QAK, 2002-07-11 */
+    fa->comm = file->comm;
+
+    FUNC_LEAVE(fa);
+} /* end H5FD_mpiposix_fapl_get() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_mpiposix_open
+ *
+ * Purpose:     Opens a file with name NAME.  The FLAGS are a bit field with
+ *		purpose similar to the second argument of open(2) and which
+ *		are defined in H5Fpublic.h. The file access property list
+ *		FAPL_ID contains the properties driver properties and MAXADDR
+ *		is the largest address which this file will be expected to
+ *		access.  This is collective.
+ *
+ * Return:      Success:        A new file pointer.
+ *              Failure:        NULL
+ *
+ * Programmer:  Quincey Koziol
+ *              Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static H5FD_t *
+H5FD_mpiposix_open(const char *name, unsigned flags, hid_t fapl_id,
+	       haddr_t maxaddr)
+{
+    H5FD_mpiposix_t		*file=NULL;     /* New MPIPOSIX file struct */
+    int                         o_flags;        /* Flags for file open call */
+    int			        fd=(-1);        /* File handle for file opened */
+    int				mpi_rank;       /* MPI rank of this process */
+    int				mpi_size;       /* Total number of MPI processes */
+    int				mpi_code;	/* mpi return code */
+    const H5FD_mpiposix_fapl_t	*fa=NULL;       /* MPIPOSIX file access property list information */
+    H5FD_mpiposix_fapl_t	_fa;            /* Private copy of default file access property list information */
+    H5P_genplist_t              *plist;         /* Property list pointer */
+    h5_stat_t                   sb;             /* Portable 'stat' struct */
+#ifdef WIN32
+    HFILE filehandle;
+    struct _BY_HANDLE_FILE_INFORMATION fileinfo;
+    int results;   
+#endif
+    H5FD_t                     *ret_value=NULL; /* Return value */
+
+    FUNC_ENTER_NOAPI(H5FD_mpiposix_open, NULL);
+
+    /* Check arguments */
+    if (!name || !*name)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "invalid file name");
+    if (0==maxaddr || HADDR_UNDEF==maxaddr)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADRANGE, NULL, "bogus maxaddr");
+    if (ADDR_OVERFLOW(maxaddr))
+        HGOTO_ERROR(H5E_ARGS, H5E_OVERFLOW, NULL, "bogus maxaddr");
+
+    /* Obtain a pointer to mpiposix-specific file access properties */
+    if(TRUE!=H5P_isa_class(fapl_id,H5P_FILE_ACCESS) || NULL == (plist = H5I_object(fapl_id)))
+        HRETURN_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list");
+    if (H5P_DEFAULT==fapl_id || H5FD_MPIPOSIX!=H5P_get_driver(plist)) {
+	_fa.comm = MPI_COMM_SELF; /*default*/
+	fa = &_fa;
+    } /* end if */
+    else {
+	fa = H5P_get_driver_info(plist);
+	assert(fa);
+    } /* end else */
+
+    /* Get the MPI rank of this process and the total number of processes */
+    if (MPI_SUCCESS != (mpi_code=MPI_Comm_rank (fa->comm, &mpi_rank)))
+        HMPI_GOTO_ERROR(NULL, "MPI_Comm_rank failed", mpi_code);
+    if (MPI_SUCCESS != (mpi_code=MPI_Comm_size (fa->comm, &mpi_size)))
+        HMPI_GOTO_ERROR(NULL, "MPI_Comm_size failed", mpi_code);
+
+    /* Build the open flags */
+    o_flags = (H5F_ACC_RDWR & flags) ? O_RDWR : O_RDONLY;
+
+    /* Only set the creation flag(s) for process 0 */
+    if(mpi_rank==0) {
+        if (H5F_ACC_TRUNC & flags)
+            o_flags |= O_TRUNC;
+        if (H5F_ACC_CREAT & flags)
+            o_flags |= O_CREAT;
+        if (H5F_ACC_EXCL & flags)
+            o_flags |= O_EXCL;
+    } /* end if */
+
+    /* Process 0 opens (or creates) the file while the rest of the
+     * processes wait.  Then process 0 signals the other processes and they
+     * open (never create) the file and all processes proceed.
+     */
+    /* Process 0 opens (or creates) file and broadcasts result to other processes */
+    if(mpi_rank==0) {
+        /* Open the file */
+        fd=HDopen(name, o_flags, 0666);
+    } /* end if */
+
+    /* Broadcast the results of the open() from process 0 */
+    /* This is necessary because of the "tentative open" code in H5F_open()
+     * where the file is attempted to be opened with different flags from the
+     * user's, in order to check for the file's existence, etc.  Here, process 0
+     * gets different flags from the other processes (since it is in charge of
+     * creating the file, if necessary) and can fail in situations where the
+     * other process's file opens would succeed, so allow the other processes
+     * to check for that situation and bail out now also. - QAK
+     */
+    if (MPI_SUCCESS != (mpi_code= MPI_Bcast(&fd, sizeof(int), MPI_BYTE, 0, fa->comm)))
+        HMPI_GOTO_ERROR(NULL, "MPI_Bcast failed", mpi_code);
+
+    /* If the file open on process 0 failed, bail out on all processes now */
+    if(fd<0)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "unable to open file");
+
+    /* Other processes (non 0) wait for broadcast result from process 0 and then open file */
+    if(mpi_rank!=0) {
+        /* Open the file */
+        if ((fd=HDopen(name, o_flags, 0666))<0)
+            HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, NULL, "unable to open file");
+    } /* end if */
+
+    /* Process 0 fstat()s the file and broadcasts the results to the other processes */
+    if(mpi_rank==0) {
+        /* Get the stat information */
+        if (HDfstat(fd, &sb)<0)
+            HGOTO_ERROR(H5E_FILE, H5E_BADFILE, NULL, "unable to fstat file");
+    } /* end if */
+
+    /* Broadcast the results of the fstat() from process 0 */
+    if (MPI_SUCCESS != (mpi_code= MPI_Bcast(&sb, sizeof(h5_stat_t), MPI_BYTE, 0, fa->comm)))
+        HMPI_GOTO_ERROR(NULL, "MPI_Bcast failed", mpi_code);
+
+    /* Build the file struct and initialize it */
+    if (NULL==(file=H5MM_calloc(sizeof(H5FD_mpiposix_t))))
+        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
+
+    /* Set the general file information */
+    file->fd = fd;
+    file->eof = sb.st_size;
+
+    /* Set the MPI information */
+    file->comm = fa->comm;
+    file->mpi_rank = mpi_rank;
+    file->mpi_size = mpi_size;
+    file->mpi_round = 0;        /* Start metadata writes with process 0 */
+
+    /* Reset the last file I/O operation */
+    file->pos = HADDR_UNDEF;
+    file->op = OP_UNKNOWN;
+
+    /* Set the information for the file's device and inode */
+#ifdef WIN32
+    filehandle = _get_osfhandle(fd);
+    results = GetFileInformationByHandle((HANDLE)filehandle, &fileinfo);
+    file->fileindexhi = fileinfo.nFileIndexHigh;
+    file->fileindexlo = fileinfo.nFileIndexLow;
+#else
+    file->device = sb.st_dev;
+    file->inode = sb.st_ino;
+#endif
+
+    /* Indicate success */
+    ret_value=(H5FD_t *)file;
+
+done:
+    /* Error cleanup */
+    if(ret_value==NULL) {
+        /* Close the file if it was left open */
+        if(fd!=(-1))
+            HDclose(fd);
+    } /* end if */
+
+    FUNC_LEAVE(ret_value);
+} /* end H5FD_mpiposix_open() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_mpiposix_close
+ *
+ * Purpose:     Closes a file.
+ *
+ * Return:      Success:	Non-negative
+ * 		Failure:	Negative
+ *
+ * Programmer:  Quincey Koziol
+ *              Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5FD_mpiposix_close(H5FD_t *_file)
+{
+    H5FD_mpiposix_t	*file = (H5FD_mpiposix_t*)_file;
+
+    FUNC_ENTER_NOAPI(H5FD_mpiposix_close, FAIL);
+
+    assert(file);
+    assert(H5FD_MPIPOSIX==file->pub.driver_id);
+
+    /* Close the unix file */
+    if (HDclose(file->fd)<0)
+        HRETURN_ERROR(H5E_IO, H5E_CANTCLOSEFILE, FAIL, "unable to close file");
+
+    H5MM_xfree(file);
+
+    FUNC_LEAVE(SUCCEED);
+} /* end H5FD_mpiposix_close() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FD_mpiposix_cmp
+ *
+ * Purpose:	Compares two files belonging to this driver using an
+ *		arbitrary (but consistent) ordering.
+ *
+ * Return:	Success:	A value like strcmp()
+ *		Failure:	never fails (arguments were checked by the
+ *				caller).
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static int
+H5FD_mpiposix_cmp(const H5FD_t *_f1, const H5FD_t *_f2)
+{
+    const H5FD_mpiposix_t	*f1 = (const H5FD_mpiposix_t*)_f1;
+    const H5FD_mpiposix_t	*f2 = (const H5FD_mpiposix_t*)_f2;
+    int ret_value=0;
+
+    FUNC_ENTER_NOAPI(H5FD_mpiposix_cmp, H5FD_VFD_DEFAULT);
+
+#ifdef WIN32
+    if (f1->fileindexhi < f2->fileindexhi) ret_value= -1;
+    if (f1->fileindexhi > f2->fileindexhi) ret_value= 1;
+
+    if (f1->fileindexlo < f2->fileindexlo) ret_value= -1;
+    if (f1->fileindexlo > f2->fileindexlo) ret_value= 1;
+
+#else
+    if (f1->device < f2->device) ret_value= -1;
+    if (f1->device > f2->device) ret_value= 1;
+
+    if (f1->inode < f2->inode) ret_value= -1;
+    if (f1->inode > f2->inode) ret_value= 1;
+#endif
+
+    FUNC_LEAVE(ret_value);
+} /* end H5FD_mpiposix_cmp() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FD_mpiposix_query
+ *
+ * Purpose:	Set the flags that this VFL driver is capable of supporting.
+ *              (listed in H5FDpublic.h)
+ *
+ * Return:	Success:	non-negative
+ *		Failure:	negative
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5FD_mpiposix_query(const H5FD_t UNUSED *_file, unsigned long *flags /* out */)
+{
+    herr_t ret_value=SUCCEED;
+
+    FUNC_ENTER_NOAPI(H5FD_mpiposix_query, FAIL);
+
+    /* Set the VFL feature flags that this driver supports */
+    if(flags) {
+        *flags=0;
+        *flags|=H5FD_FEAT_AGGREGATE_METADATA; /* OK to aggregate metadata allocations */
+
+        /* Distinguish between updating the metadata accumulator on writes and
+         * reads.  This is particularly (perhaps only, even) important for MPI-I/O
+         * where we guarantee that writes are collective, but reads may not be.
+         * If we were to allow the metadata accumulator to be written during a
+         * read operation, the application would hang.
+         */
+        *flags|=H5FD_FEAT_ACCUMULATE_METADATA_WRITE; /* OK to accumulate metadata for faster writes */
+
+        *flags|=H5FD_FEAT_AGGREGATE_SMALLDATA; /* OK to aggregate "small" raw data allocations */
+    } /* end if */
+
+    FUNC_LEAVE(ret_value);
+} /* end H5FD_mpiposix_query() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FD_mpiposix_get_eoa
+ *
+ * Purpose:	Gets the end-of-address marker for the file. The EOA marker
+ *		is the first address past the last byte allocated in the
+ *		format address space.
+ *
+ * Return:	Success:	The end-of-address marker.
+ *		Failure:	HADDR_UNDEF
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static haddr_t
+H5FD_mpiposix_get_eoa(H5FD_t *_file)
+{
+    H5FD_mpiposix_t *file = (H5FD_mpiposix_t*)_file;
+
+    FUNC_ENTER_NOAPI(H5FD_mpiposix_get_eoa, HADDR_UNDEF);
+
+    assert(file);
+    assert(H5FD_MPIPOSIX==file->pub.driver_id);
+
+    FUNC_LEAVE(file->eoa);
+} /* end H5FD_mpiposix_get_eoa() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FD_mpiposix_set_eoa
+ *
+ * Purpose:	Set the end-of-address marker for the file. This function is
+ *		called shortly after an existing HDF5 file is opened in order
+ *		to tell the driver where the end of the HDF5 data is located.
+ *
+ * Return:	Success:	non-negative
+ *		Failure:	negative
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5FD_mpiposix_set_eoa(H5FD_t *_file, haddr_t addr)
+{
+    H5FD_mpiposix_t	*file = (H5FD_mpiposix_t*)_file;
+
+    FUNC_ENTER_NOAPI(H5FD_mpiposix_set_eoa, FAIL);
+
+    assert(file);
+    assert(H5FD_MPIPOSIX==file->pub.driver_id);
+
+    file->eoa = addr;
+
+    FUNC_LEAVE(SUCCEED);
+} /* end H5FD_mpi_posix_set_eoa() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FD_mpiposix_get_eof
+ *
+ * Purpose:	Gets the end-of-file marker for the file. The EOF marker
+ *		is the real size of the file.
+ *
+ *		The MPIPOSIX driver doesn't bother keeping this field updated
+ *		since that's a relatively expensive operation. Fortunately
+ *		the library only needs the EOF just after the file is opened
+ *		in order to determine whether the file is empty, truncated,
+ *		or okay.
+ *
+ * Return:	Success:	The end-of-address marker.
+ *		Failure:	HADDR_UNDEF
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static haddr_t
+H5FD_mpiposix_get_eof(H5FD_t *_file)
+{
+    H5FD_mpiposix_t	*file = (H5FD_mpiposix_t*)_file;
+
+    FUNC_ENTER_NOAPI(H5FD_mpiposix_get_eof, HADDR_UNDEF);
+
+    assert(file);
+    assert(H5FD_MPIPOSIX==file->pub.driver_id);
+
+    FUNC_LEAVE(MAX(file->eof,file->eoa));
+} /* end H5FD_mpiposix_get_eof() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FD_mpiposix_read
+ *
+ * Purpose:	Reads SIZE bytes of data from FILE beginning at address ADDR
+ *		into buffer BUF according to data transfer properties in
+ *		DXPL_ID using potentially complex file and buffer types to
+ *		effect the transfer.
+ *
+ *		Reading past the end of the file returns zeros instead of
+ *		failing.
+ *
+ * Return:	Success:	Non-negative. Result is stored in caller-supplied
+ *				buffer BUF.
+ *		Failure:	Negative, Contents of buffer BUF are undefined.
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5FD_mpiposix_read(H5FD_t *_file, H5FD_mem_t UNUSED type, hid_t UNUSED dxpl_id, haddr_t addr, size_t size,
+	       void *buf/*out*/)
+{
+    H5FD_mpiposix_t	*file = (H5FD_mpiposix_t*)_file;
+    ssize_t	        nbytes;         /* Number of bytes read each I/O call */
+    herr_t             	ret_value=SUCCEED;
+
+    FUNC_ENTER_NOAPI(H5FD_mpiposix_read, FAIL);
+
+    assert(file);
+    assert(H5FD_MPIPOSIX==file->pub.driver_id);
+    assert(buf);
+
+    /* Check for overflow conditions */
+    if (HADDR_UNDEF==addr)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "addr undefined");
+    if (REGION_OVERFLOW(addr, size))
+        HGOTO_ERROR(H5E_ARGS, H5E_OVERFLOW, FAIL, "addr overflow");
+    if (addr+size>file->eoa)
+        HGOTO_ERROR(H5E_ARGS, H5E_OVERFLOW, FAIL, "addr overflow");
+
+    /* Seek to the correct location */
+    if ((addr!=file->pos || OP_READ!=file->op) &&
+            file_seek(file->fd, (file_offset_t)addr, SEEK_SET)<0)
+        HGOTO_ERROR(H5E_IO, H5E_SEEKERROR, FAIL, "unable to seek to proper position");
+
+    /*
+     * Read data, being careful of interrupted system calls, partial results,
+     * and the end of the file.
+     */
+    while (size>0) {
+        do {
+            nbytes = HDread(file->fd, buf, size);
+        } while (-1==nbytes && EINTR==errno);
+        if (-1==nbytes)
+            HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "file read failed");
+        if (0==nbytes) {
+            /* end of file but not end of format address space */
+            HDmemset(buf, 0, size);
+            size = 0;
+        } /* end if */
+        assert(nbytes>=0);
+        assert((size_t)nbytes<=size);
+        size -= nbytes;
+        addr += (haddr_t)nbytes;
+        buf = (char*)buf + nbytes;
+    }
+    
+    /* Update current position */
+    file->pos = addr;
+    file->op = OP_READ;
+
+done:
+    /* Check for error */
+    if(ret_value<0) {
+        /* Reset last file I/O information */
+        file->pos = HADDR_UNDEF;
+        file->op = OP_UNKNOWN;
+    } /* end if */
+
+    FUNC_LEAVE(ret_value);
+} /* end H5FD_mpiposix_read() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FD_mpiposix_write
+ *
+ * Purpose:	Writes SIZE bytes of data to FILE beginning at address ADDR
+ *		from buffer BUF according to data transfer properties in
+ *		DXPL_ID using potentially complex file and buffer types to
+ *		effect the transfer.
+ *
+ * Return:	Success:	non-negative
+ *		Failure:	negative
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5FD_mpiposix_write(H5FD_t *_file, H5FD_mem_t type, hid_t UNUSED dxpl_id, haddr_t addr,
+		size_t size, const void *buf)
+{
+    H5FD_mpiposix_t	*file = (H5FD_mpiposix_t*)_file;
+    int			mpi_code;	/* MPI return code */
+    ssize_t	        nbytes;         /* Number of bytes written each I/O call */
+    herr_t             	ret_value=SUCCEED;      /* Return value */
+
+    FUNC_ENTER_NOAPI(H5FD_mpiposix_write, FAIL);
+
+    assert(file);
+    assert(H5FD_MPIPOSIX==file->pub.driver_id);
+    assert(buf);
+
+    /* Check for overflow conditions */
+    if (HADDR_UNDEF==addr) 
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "addr undefined");
+    if (REGION_OVERFLOW(addr, size))
+        HGOTO_ERROR(H5E_ARGS, H5E_OVERFLOW, FAIL, "addr overflow");
+    if (addr+size>file->eoa)
+        HGOTO_ERROR(H5E_ARGS, H5E_OVERFLOW, FAIL, "addr overflow");
+    
+    /* Only p<round> will do the actual write if all procs in comm write same data */
+    if ((type!=H5FD_MEM_DRAW) && H5_mpiposix_1_metawrite_g) {
+        if (file->mpi_rank != file->mpi_round)
+            HGOTO_DONE(SUCCEED) /* skip the actual write */
+    } /* end if */
+
+    /* Seek to the correct location */
+    if ((addr!=file->pos || OP_WRITE!=file->op) &&
+            file_seek(file->fd, (file_offset_t)addr, SEEK_SET)<0)
+        HGOTO_ERROR(H5E_IO, H5E_SEEKERROR, FAIL,
+		      "unable to seek to proper position");
+
+    /*
+     * Write the data, being careful of interrupted system calls and partial
+     * results
+     */
+    while (size>0) {
+        do {
+            nbytes = HDwrite(file->fd, buf, size);
+        } while (-1==nbytes && EINTR==errno);
+        if (-1==nbytes)
+            HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "file write failed");
+        assert(nbytes>0);
+        assert((size_t)nbytes<=size);
+        size -= nbytes;
+        addr += (haddr_t)nbytes;
+        buf = (const char*)buf + nbytes;
+    } /* end while */
+
+    /* Update current last file I/O information */
+    file->pos = addr;
+    file->op = OP_WRITE;
+
+done:
+    /* Check for error */
+    if(ret_value<0) {
+        /* Reset last file I/O information */
+        file->pos = HADDR_UNDEF;
+        file->op = OP_UNKNOWN;
+    } /* end if */
+    /* Guard against getting into metadata broadcast in failure cases */
+    else {
+        /* if only p<round> writes, need to broadcast the ret_value to other processes */
+        if ((type!=H5FD_MEM_DRAW) && H5_mpiposix_1_metawrite_g) {
+            if (MPI_SUCCESS != (mpi_code= MPI_Bcast(&ret_value, sizeof(ret_value), MPI_BYTE, file->mpi_round, file->comm)))
+                HMPI_GOTO_ERROR(FAIL, "MPI_Bcast failed", mpi_code);
+
+            /* Round-robin rotate to the next process */
+            file->mpi_round = (++file->mpi_round)%file->mpi_size;
+#ifdef QAK
+    {
+        int max,min;
+
+        MPI_Allreduce(&file->mpi_round, &max, 1, MPI_INT, MPI_MAX, file->comm);
+        MPI_Allreduce(&file->mpi_round, &min, 1, MPI_INT, MPI_MIN, file->comm);
+        if(max!=file->mpi_round)
+            printf("%s: rank=%d, round=%d, max=%d\n",FUNC,file->mpi_rank,file->mpi_round,max);
+        if(min!=file->mpi_round)
+            printf("%s: rank=%d, round=%d, min=%d\n",FUNC,file->mpi_rank,file->mpi_round,min);
+    }
+#endif /* QAK */
+        } /* end if */
+    } /* end else */
+
+    FUNC_LEAVE(ret_value);
+} /* end H5FD_mpiposix_write() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5FD_mpiposix_flush
+ *
+ * Purpose:     Makes sure that all data is on disk.  This is collective.
+ *
+ * Return:      Success:	Non-negative
+ * 		Failure:	Negative
+ *
+ * Programmer:  Quincey Koziol
+ *              Thursday, July 11, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5FD_mpiposix_flush(H5FD_t *_file, unsigned UNUSED closing)
+{
+    H5FD_mpiposix_t	*file = (H5FD_mpiposix_t*)_file;
+#ifdef WIN32
+    HFILE filehandle;   /* Windows file handle */
+    LARGE_INTEGER li;   /* 64-bit integer for SetFilePointer() call */
+#endif /* WIN32 */
+    int			mpi_code;	/* MPI return code */
+    herr_t              ret_value=SUCCEED;
+
+    FUNC_ENTER_NOAPI(H5FD_mpiposix_flush, FAIL);
+
+    assert(file);
+    assert(H5FD_MPIPOSIX==file->pub.driver_id);
+
+    /* Extend the file to make sure it's large enough */
+    if(file->eoa>file->last_eoa) {
+        /* Use the round-robin process to truncate (extend) the file */
+        if(file->mpi_rank == file->mpi_round) {
+#ifdef WIN32
+            /* Map the posix file handle to a Windows file handle */
+            filehandle = _get_osfhandle(fd);
+
+            /* Translate 64-bit integers into form Windows wants */
+            /* [This algorithm is from the Windows documentation for SetFilePointer()] */
+            li.QuadPart = file->eoa;
+            SetFilePointer((HANDLE)filehandle,li.LowPart,&li.HighPart,FILE_BEGIN);
+            if(SetEndOfFile((HANDLE)filehandle)==0)
+                HGOTO_ERROR(H5E_IO, H5E_SEEKERROR, FAIL, "unable to extend file properly");
+#else /* WIN32 */
+            if(-1==file_truncate(file->fd, (file_offset_t)file->eoa))
+                HGOTO_ERROR(H5E_IO, H5E_SEEKERROR, FAIL, "unable to extend file properly");
+#endif /* WIN32 */
+        } /* end if */
+
+        /* Don't let any proc return until all have extended the file.
+         * (Prevents race condition where some processes go ahead and write
+         * more data to the file before all the processes have finished making
+         * it the shorter length, potentially truncating the file and dropping
+         * the new data written)
+         */
+        if (MPI_SUCCESS!= (mpi_code=MPI_Barrier(file->comm)))
+            HMPI_GOTO_ERROR(FAIL, "MPI_Barrier failed", mpi_code);
+
+        /* Update the 'last' eoa and eof values */
+        file->last_eoa=file->eoa;
+        file->eof = file->eoa;
+
+        /* Reset last file I/O information */
+        file->pos = HADDR_UNDEF;
+        file->op = OP_UNKNOWN;
+    } /* end if */
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5FD_mpiposix_flush() */
+
+#endif /*H5_HAVE_PARALLEL*/
+
diff --git a/src/H5FDmpiposix.h b/src/H5FDmpiposix.h
new file mode 100644
index 0000000..81d05d4
--- /dev/null
+++ b/src/H5FDmpiposix.h
@@ -0,0 +1,62 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+ * Copyright by the Board of Trustees of the University of Illinois.         *
+ * All rights reserved.                                                      *
+ *                                                                           *
+ * This file is part of HDF5.  The full HDF5 copyright notice, including     *
+ * terms governing use, modification, and redistribution, is contained in    *
+ * the files COPYING and Copyright.html.  COPYING can be found at the root   *
+ * of the source code distribution tree; Copyright.html can be found at the  *
+ * root level of an installed copy of the electronic HDF5 document set and   *
+ * is linked from the top-level documents page.  It can also be found at     *
+ * http://hdf.ncsa.uiuc.edu/HDF5/doc/Copyright.html.  If you do not have     *
+ * access to either file, you may request a copy from hdfhelp@ncsa.uiuc.edu. *
+ * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/*
+ * Programmer:  Quincey Koziol <koziol@ncsa.uiuc.edu>
+ *              Thursday, July 11, 2002
+ *
+ * Purpose:	The public header file for the mpiposix driver.
+ */
+
+#ifndef __H5FDmpiposix_H
+#define __H5FDmpiposix_H
+
+#include "H5FDpublic.h"
+#include "H5Ipublic.h"
+
+#ifdef H5_HAVE_PARALLEL
+#   define H5FD_MPIPOSIX	(H5FD_mpiposix_init())
+#else
+#   define H5FD_MPIPOSIX	(-1)
+#endif
+
+#ifdef H5_HAVE_PARALLEL
+
+/* Macros */
+
+#define IS_H5FD_MPIPOSIX(f)	/* (H5F_t *f) */				    \
+    (H5FD_MPIPOSIX==H5F_get_driver_id(f))
+
+/* Function prototypes */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+__DLL__ hid_t H5FD_mpiposix_init(void);
+__DLL__ herr_t H5Pset_fapl_mpiposix(hid_t fapl_id, MPI_Comm comm);
+__DLL__ herr_t H5Pget_fapl_mpiposix(hid_t fapl_id, MPI_Comm *comm/*out*/);
+__DLL__ MPI_Comm H5FD_mpiposix_communicator(H5FD_t *_file);
+__DLL__ herr_t H5FD_mpiposix_closing(H5FD_t *file);
+__DLL__ int H5FD_mpiposix_mpi_rank(H5FD_t *_file);
+__DLL__ int H5FD_mpiposix_mpi_size(H5FD_t *_file);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /*H5_HAVE_PARALLEL*/
+
+#endif /* __H5FDmpiposix_H */
+
+
diff --git a/src/H5Farray.c b/src/H5Farray.c
index cefed52..d2f84be 100644
--- a/src/H5Farray.c
+++ b/src/H5Farray.c
@@ -171,27 +171,29 @@ H5F_arr_read(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
 
 #ifdef H5_HAVE_PARALLEL
     {
-	/* Get the transfer mode */
 	H5FD_mpio_dxpl_t *dx;
         hid_t driver_id;            /* VFL driver ID */
 
-        /* Get the plist structure */
-        if(NULL == (plist = H5I_object(dxpl_id)))
-            HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
-
-        /* Get the driver ID */
-        if(H5P_get(plist, H5D_XFER_VFL_ID_NAME, &driver_id)<0)
-            HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver ID");
-
-        /* Check if we are using the MPIO driver */
-        if(H5FD_MPIO==driver_id) {
-            /* Get the driver information */
-            if(H5P_get(plist, H5D_XFER_VFL_INFO_NAME, &dx)<0)
-                HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver info");
-
-            /* Check if we are not using independent I/O */
-            if(H5FD_MPIO_INDEPENDENT!=dx->xfer_mode)
-                xfer_mode = dx->xfer_mode;
+	/* Get the transfer mode for MPIO transfers */
+        if(IS_H5FD_MPIO(f)) {
+            /* Get the plist structure */
+            if(NULL == (plist = H5I_object(dxpl_id)))
+                HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
+
+            /* Get the driver ID */
+            if(H5P_get(plist, H5D_XFER_VFL_ID_NAME, &driver_id)<0)
+                HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver ID");
+
+            /* Check if we are using the MPIO driver (for the DXPL) */
+            if(H5FD_MPIO==driver_id) {
+                /* Get the driver information */
+                if(H5P_get(plist, H5D_XFER_VFL_INFO_NAME, &dx)<0)
+                    HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver info");
+
+                /* Check if we are not using independent I/O */
+                if(H5FD_MPIO_INDEPENDENT!=dx->xfer_mode)
+                    xfer_mode = dx->xfer_mode;
+            } /* end if */
         } /* end if */
     }
     
@@ -412,27 +414,29 @@ H5F_arr_write(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
 
 #ifdef H5_HAVE_PARALLEL
     {
-	/* Get the transfer mode */
 	H5FD_mpio_dxpl_t *dx;
         hid_t driver_id;            /* VFL driver ID */
 
-        /* Get the plist structure */
-        if(NULL == (plist = H5I_object(dxpl_id)))
-            HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
-
-        /* Get the driver ID */
-        if(H5P_get(plist, H5D_XFER_VFL_ID_NAME, &driver_id)<0)
-            HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver ID");
-
-        /* Check if we are using the MPIO driver */
-        if(H5FD_MPIO==driver_id) {
-            /* Get the driver information */
-            if(H5P_get(plist, H5D_XFER_VFL_INFO_NAME, &dx)<0)
-                HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver info");
-
-            /* Check if we are not using independent I/O */
-            if(H5FD_MPIO_INDEPENDENT!=dx->xfer_mode)
-                xfer_mode = dx->xfer_mode;
+	/* Get the transfer mode for MPIO transfers */
+        if(IS_H5FD_MPIO(f)) {
+            /* Get the plist structure */
+            if(NULL == (plist = H5I_object(dxpl_id)))
+                HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
+
+            /* Get the driver ID */
+            if(H5P_get(plist, H5D_XFER_VFL_ID_NAME, &driver_id)<0)
+                HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver ID");
+
+            /* Check if we are using the MPIO driver (for the DXPL) */
+            if(H5FD_MPIO==driver_id) {
+                /* Get the driver information */
+                if(H5P_get(plist, H5D_XFER_VFL_INFO_NAME, &dx)<0)
+                    HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver info");
+
+                /* Check if we are not using independent I/O */
+                if(H5FD_MPIO_INDEPENDENT!=dx->xfer_mode)
+                    xfer_mode = dx->xfer_mode;
+            } /* end if */
         } /* end if */
     }
     
diff --git a/src/H5Fistore.c b/src/H5Fistore.c
index a44ce5a..a9f7f56 100644
--- a/src/H5Fistore.c
+++ b/src/H5Fistore.c
@@ -45,8 +45,9 @@
 #include "H5Sprivate.h"         /* Dataspaces */
 #include "H5Vprivate.h"
 
-/* MPIO driver needed for special checks */
+/* MPIO & MPIPOSIX drivers needed for special checks */
 #include "H5FDmpio.h"
+#include "H5FDmpiposix.h"
 
 /*
  * Feature: If this constant is defined then every cache preemption and load
@@ -1781,12 +1782,12 @@ H5F_istore_read(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
 
 #ifdef H5_HAVE_PARALLEL
         /*
-         * If MPIO is used and file can be written to, we must bypass the
+         * If MPIO or MPIPOSIX is used and file can be written to, we must bypass the
          * chunk-cache scheme because other MPI processes could be writing to
          * other elements in the same chunk.
          * Do a direct write-through of only the elements requested.
          */
-            || (IS_H5FD_MPIO(f) && (H5F_ACC_RDWR & f->shared->flags))
+            || ((IS_H5FD_MPIO(f) ||IS_H5FD_MPIPOSIX(f)) && (H5F_ACC_RDWR & f->shared->flags))
 #endif /* H5_HAVE_PARALLEL */
             ) {
             H5O_layout_t	l;	/* temporary layout */
@@ -1965,11 +1966,11 @@ H5F_istore_write(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
 
 #ifdef H5_HAVE_PARALLEL
         /*
-         * If MPIO is used, must bypass the chunk-cache scheme because other
+         * If MPIO or MPIPOSIX is used, must bypass the chunk-cache scheme because other
          * MPI processes could be writing to other elements in the same chunk.
          * Do a direct write-through of only the elements requested.
          */
-            || (IS_H5FD_MPIO(f) && (H5F_ACC_RDWR & f->shared->flags))
+            || ((IS_H5FD_MPIO(f) ||IS_H5FD_MPIPOSIX(f)) && (H5F_ACC_RDWR & f->shared->flags))
 #endif /* H5_HAVE_PARALLEL */
             ) {
             H5O_layout_t	l;	/* temporary layout */
@@ -2416,10 +2417,22 @@ H5F_istore_allocate(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
     } /* end if */
 
     /* Retrieve up MPI parameters */
-    if ((mpi_rank=H5FD_mpio_mpi_rank(f->shared->lf))<0)
-        HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "Can't retrieve MPI rank");
-    if ((mpi_size=H5FD_mpio_mpi_size(f->shared->lf))<0)
-        HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "Can't retrieve MPI size");
+    if(IS_H5FD_MPIO(f)) {
+        if ((mpi_rank=H5FD_mpio_mpi_rank(f->shared->lf))<0)
+            HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "Can't retrieve MPI rank");
+        if ((mpi_size=H5FD_mpio_mpi_size(f->shared->lf))<0)
+            HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "Can't retrieve MPI size");
+    } /* end if */
+    else {
+        /* Sanity Check */
+        assert(IS_H5FD_MPIPOSIX(f));
+
+        /* Get the MPI rank & size */
+        if ((mpi_rank=H5FD_mpiposix_mpi_rank(f->shared->lf))<0)
+            HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "Can't retrieve MPI rank");
+        if ((mpi_size=H5FD_mpiposix_mpi_size(f->shared->lf))<0)
+            HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "Can't retrieve MPI size");
+    } /* end else */
 
     /* Loop over all chunks */
     carry=0;
@@ -2469,8 +2482,17 @@ H5F_istore_allocate(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
          * still writing out chunks and other processes race ahead to read
          * them in, getting bogus data.
          */
-        if (MPI_Barrier(H5FD_mpio_communicator(f->shared->lf)))
-            HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "MPI_Barrier failed");
+        if(IS_H5FD_MPIO(f)) {
+            if (MPI_Barrier(H5FD_mpio_communicator(f->shared->lf)))
+                HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "MPI_Barrier failed");
+        } /* end if */
+        else {
+            /* Sanity Check */
+            assert(IS_H5FD_MPIPOSIX(f));
+
+            if (MPI_Barrier(H5FD_mpiposix_communicator(f->shared->lf)))
+                HGOTO_ERROR(H5E_INTERNAL, H5E_MPI, FAIL, "MPI_Barrier failed");
+        } /* end else */
     } /* end if */
 
 done:
diff --git a/src/H5Fpkg.h b/src/H5Fpkg.h
index 10ed39b..189cbc7 100644
--- a/src/H5Fpkg.h
+++ b/src/H5Fpkg.h
@@ -161,6 +161,7 @@ struct H5F_t {
 
 #ifdef H5_HAVE_PARALLEL
 __DLLVAR__  hbool_t H5_mpi_1_metawrite_g;
+__DLLVAR__  hbool_t H5_mpiposix_1_metawrite_g;
 #endif /* H5_HAVE_PARALLEL */
 
 /* Private functions, not part of the publicly documented API */
diff --git a/src/H5Fseq.c b/src/H5Fseq.c
index 0a4da84..8f988ff 100644
--- a/src/H5Fseq.c
+++ b/src/H5Fseq.c
@@ -26,8 +26,9 @@
 #include "H5Pprivate.h"
 #include "H5Vprivate.h"
 
-/* MPIO driver functions are needed for some special checks */
+/* MPIO & MPIPOSIX driver functions are needed for some special checks */
 #include "H5FDmpio.h"
+#include "H5FDmpiposix.h"
 
 /* Interface initialization */
 #define PABLO_MASK	H5Fseq_mask
@@ -182,27 +183,29 @@ H5F_seq_readv(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
 
 #ifdef H5_HAVE_PARALLEL
     {
-	/* Get the transfer mode */
 	H5FD_mpio_dxpl_t *dx;
         hid_t driver_id;            /* VFL driver ID */
 
-        /* Get the plist structure */
-        if(NULL == (plist = H5I_object(dxpl_id)))
-            HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
-
-        /* Get the driver ID */
-        if(H5P_get(plist, H5D_XFER_VFL_ID_NAME, &driver_id)<0)
-            HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver ID");
-
-        /* Check if we are using the MPIO driver */
-        if(H5FD_MPIO==driver_id) {
-            /* Get the driver information */
-            if(H5P_get(plist, H5D_XFER_VFL_INFO_NAME, &dx)<0)
-                HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver info");
-
-            /* Check if we are not using independent I/O */
-            if(H5FD_MPIO_INDEPENDENT!=dx->xfer_mode)
-                xfer_mode = dx->xfer_mode;
+	/* Get the transfer mode for MPIO transfers */
+        if(IS_H5FD_MPIO(f)) {
+            /* Get the plist structure */
+            if(NULL == (plist = H5I_object(dxpl_id)))
+                HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
+
+            /* Get the driver ID */
+            if(H5P_get(plist, H5D_XFER_VFL_ID_NAME, &driver_id)<0)
+                HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver ID");
+
+            /* Check if we are using the MPIO driver (for the DXPL) */
+            if(H5FD_MPIO==driver_id) {
+                /* Get the driver information */
+                if(H5P_get(plist, H5D_XFER_VFL_INFO_NAME, &dx)<0)
+                    HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver info");
+
+                /* Check if we are not using independent I/O */
+                if(H5FD_MPIO_INDEPENDENT!=dx->xfer_mode)
+                    xfer_mode = dx->xfer_mode;
+            } /* end if */
         } /* end if */
     }
 
@@ -564,27 +567,29 @@ H5F_seq_writev(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
 
 #ifdef H5_HAVE_PARALLEL
     {
-	/* Get the transfer mode */
 	H5FD_mpio_dxpl_t *dx;
         hid_t driver_id;            /* VFL driver ID */
 
-        /* Get the plist structure */
-        if(NULL == (plist = H5I_object(dxpl_id)))
-            HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
-
-        /* Get the driver ID */
-        if(H5P_get(plist, H5D_XFER_VFL_ID_NAME, &driver_id)<0)
-            HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver ID");
-
-        /* Check if we are using the MPIO driver */
-        if(H5FD_MPIO==driver_id) {
-            /* Get the driver information */
-            if(H5P_get(plist, H5D_XFER_VFL_INFO_NAME, &dx)<0)
-                HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver info");
-
-            /* Check if we are not using independent I/O */
-            if(H5FD_MPIO_INDEPENDENT!=dx->xfer_mode)
-                xfer_mode = dx->xfer_mode;
+	/* Get the transfer mode for MPIO transfers */
+        if(IS_H5FD_MPIO(f)) {
+            /* Get the plist structure */
+            if(NULL == (plist = H5I_object(dxpl_id)))
+                HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
+
+            /* Get the driver ID */
+            if(H5P_get(plist, H5D_XFER_VFL_ID_NAME, &driver_id)<0)
+                HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver ID");
+
+            /* Check if we are using the MPIO driver (for the DXPL) */
+            if(H5FD_MPIO==driver_id) {
+                /* Get the driver information */
+                if(H5P_get(plist, H5D_XFER_VFL_INFO_NAME, &dx)<0)
+                    HGOTO_ERROR (H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve VFL driver info");
+
+                /* Check if we are not using independent I/O */
+                if(H5FD_MPIO_INDEPENDENT!=dx->xfer_mode)
+                    xfer_mode = dx->xfer_mode;
+            } /* end if */
         } /* end if */
     }
 
diff --git a/src/Makefile.in b/src/Makefile.in
index 8875f15..78aef12 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -20,8 +20,8 @@ CLEAN=libhdf5.settings
 
 ## Source and object files for the library (lexicographically)...
 LIB_SRC=H5.c H5A.c H5AC.c H5B.c H5D.c H5E.c H5F.c H5Farray.c H5Fcontig.c \
-    H5Fistore.c H5Fseq.c H5FD.c H5FDsec2.c H5FDfamily.c H5FDmpio.c H5FDcore.c \
-    H5FDmulti.c H5FDgass.c H5FDlog.c H5FDsrb.c H5FDstdio.c \
+    H5Fistore.c H5Fseq.c H5FD.c H5FDcore.c H5FDfamily.c H5FDgass.c H5FDlog.c \
+    H5FDmpio.c H5FDmpiposix.c H5FDmulti.c H5FDsec2.c H5FDsrb.c H5FDstdio.c \
     H5FDstream.c H5FL.c H5G.c H5Gent.c H5Gnode.c H5Gstab.c H5HG.c H5HL.c H5I.c \
     H5MF.c H5MM.c H5O.c H5Oattr.c H5Ocomp.c H5Ocont.c H5Odtype.c H5Oefl.c \
     H5Ofill.c H5Olayout.c H5Omtime.c H5Oname.c H5Onull.c H5Osdspace.c \
@@ -37,11 +37,11 @@ MOSTLYCLEAN=H5detect.o H5detect.lo H5detect H5Tinit.o H5Tinit.lo H5Tinit.c
 
 ## Public header files (to be installed)...
 PUB_HDR=H5public.h H5Apublic.h H5ACpublic.h H5Bpublic.h H5Dpublic.h H5Epublic.h	\
-    H5Fpublic.h H5FDpublic.h H5FDfamily.h H5FDgass.h H5FDmpio.h	\
-    H5FDlog.h H5FDsec2.h H5FDsrb.h H5FDstream.h H5FDcore.h H5FDmulti.h		\
-    H5FDstdio.h H5Gpublic.h H5HGpublic.h H5HLpublic.h H5Ipublic.h H5MMpublic.h  \
-    H5Opublic.h H5Ppublic.h H5Rpublic.h H5Spublic.h H5Tpublic.h H5Zpublic.h	\
-    H5pubconf.h hdf5.h H5api_adpt.h
+    H5Fpublic.h H5FDpublic.h H5FDcore.h H5FDfamily.h H5FDgass.h H5FDlog.h \
+    H5FDmpio.h H5FDmpiposix.h H5FDmulti.h H5FDsec2.h H5FDsrb.h H5FDstdio.h \
+    H5FDstream.h H5Gpublic.h H5HGpublic.h H5HLpublic.h H5Ipublic.h \
+    H5MMpublic.h H5Opublic.h H5Ppublic.h H5Rpublic.h H5Spublic.h H5Tpublic.h \
+    H5Zpublic.h	H5pubconf.h hdf5.h H5api_adpt.h
 
 ## Other header files (not to be installed)...
 PRIVATE_HDR=H5private.h H5Aprivate.h H5Apkg.h H5ACprivate.h H5Bprivate.h \
diff --git a/src/hdf5.h b/src/hdf5.h
index a5bd15b..e7657a3 100644
--- a/src/hdf5.h
+++ b/src/hdf5.h
@@ -41,13 +41,14 @@
 /* Predefined file drivers */
 #include "H5FDcore.h"		/* Files stored entirely in memory	*/
 #include "H5FDfamily.h"		/* File families 			*/
+#include "H5FDgass.h"		/* Remote files using GASS I/O		*/
+#include "H5FDlog.h"        	/* sec2 driver with I/O logging (for debugging) */
 #include "H5FDmpio.h"		/* Parallel files using MPI-2 I/O	*/
+#include "H5FDmpiposix.h"	/* Parallel files using combination MPI-2 & posix I/O */
+#include "H5FDmulti.h"		/* Usage-partitioned file family	*/
 #include "H5FDsec2.h"		/* POSIX unbuffered file I/O		*/
-#include "H5FDstdio.h"		/* Standard C buffered I/O		*/
 #include "H5FDsrb.h"        	/* Remote access using SRB              */
-#include "H5FDgass.h"		/* Remote files using GASS I/O		*/
-#include "H5FDstream.h"     	/* in-memory files streamed via sockets */
-#include "H5FDmulti.h"		/* Usage-partitioned file family	*/
-#include "H5FDlog.h"        	/* sec2 driver with I/O logging (for debugging) */
+#include "H5FDstdio.h"		/* Standard C buffered I/O		*/
+#include "H5FDstream.h"     	/* In-memory files streamed via sockets */
 
 #endif