diff -Naur mpich2-1.2.1p1.ORIG/src/mpi/romio/adio/common/ad_fstype.c mpich2-1.2.1p1/src/mpi/romio/adio/common/ad_fstype.c
--- mpich2-1.2.1p1.ORIG/src/mpi/romio/adio/common/ad_fstype.c	2009-06-01 16:57:33.000000000 -0600
+++ mpich2-1.2.1p1/src/mpi/romio/adio/common/ad_fstype.c	2010-03-10 11:35:34.701131000 -0700
@@ -504,9 +504,12 @@
 	*fstype = ADIO_NFS;
     }
     else if (!strncmp(filename, "panfs:", 6) || !strncmp(filename, "PANFS:", 6)) {
-	*fstype = ADIO_PANFS;
+        *fstype = ADIO_PANFS;
     }
-    else if (!strncmp(filename, "hfs:", 4) || !strncmp(filename, "HFS:", 4)) {
+    else if (!strncmp(filename, "plfs:", 5) || !strncmp(filename, "PLFS:", 5)) {
+	*fstype = ADIO_PLFS;
+    }
+    else if (!strncmp(filename, "hfs:", 4) || !strncmp(filename, "HFS:", 4)) {
 	*fstype = ADIO_HFS;
     }
     else if (!strncmp(filename, "xfs:", 4) || !strncmp(filename, "XFS:", 4)) {
@@ -708,6 +711,16 @@
 	*ops = &ADIO_PANFS_operations;
 #endif
     }
+    if (file_system == ADIO_PLFS) {
+#ifndef ROMIO_PLFS
+        *error_code = MPIO_Err_create_code(MPI_SUCCESS, MPIR_ERR_RECOVERABLE,
+                                           myname, __LINE__, MPI_ERR_IO,
+                                           "**iofstypeunsupported", 0);
+        return;
+#else
+        *ops = &ADIO_PLFS_operations;
+#endif
+    }
     if (file_system == ADIO_HFS) {
 #ifndef ROMIO_HFS
 	*error_code = MPIO_Err_create_code(MPI_SUCCESS, MPIR_ERR_RECOVERABLE,
diff -Naur mpich2-1.2.1p1.ORIG/src/mpi/romio/adio/include/adio.h mpich2-1.2.1p1/src/mpi/romio/adio/include/adio.h
--- mpich2-1.2.1p1.ORIG/src/mpi/romio/adio/include/adio.h	2009-08-05 16:43:28.000000000 -0600
+++ mpich2-1.2.1p1/src/mpi/romio/adio/include/adio.h	2010-03-10 11:39:08.801355000 -0700
@@ -288,6 +288,7 @@
 #define ADIO_LUSTRE              163   /* Lustre */
 #define ADIO_BGL                 164   /* IBM BGL */
 #define ADIO_BGLOCKLESS          165   /* IBM BGL (lock-free) */
+#define ADIO_PLFS                166   /* PLFS */
 #define ADIO_ZOIDFS              167   /* ZoidFS: the I/O forwarding fs */
 
 #define ADIO_SEEK_SET            SEEK_SET
diff -Naur mpich2-1.2.1p1.ORIG/src/mpi/romio/adio/include/adioi_errmsg.h mpich2-1.2.1p1/src/mpi/romio/adio/include/adioi_errmsg.h
--- mpich2-1.2.1p1.ORIG/src/mpi/romio/adio/include/adioi_errmsg.h	2008-11-06 14:29:57.000000000 -0700
+++ mpich2-1.2.1p1/src/mpi/romio/adio/include/adioi_errmsg.h	2010-03-10 11:37:41.292577000 -0700
@@ -42,7 +42,7 @@
 
 MPI_ERR_IO
     MPIR_ERR_ETYPE_FRACTIONAL "Only an integral number of etypes can be accessed"
-    MPIR_ERR_NO_FSTYPE "Can't determine the file-system type. Check the filename/path you provided and try again. Otherwise, prefix the filename with a string to indicate the type of file sytem (piofs:, pfs:, nfs:, ufs:, hfs:, xfs:, sfs:, pvfs:, panfs: ftp: gsiftp:)"
+    MPIR_ERR_NO_FSTYPE "Can't determine the file-system type. Check the filename/path you provided and try again. Otherwise, prefix the filename with a string to indicate the type of file sytem (piofs:, pfs:, nfs:, ufs:, hfs:, xfs:, sfs:, pvfs:, panfs: plfs: ftp: gsiftp:)"
     MPIR_ERR_NO_PFS "ROMIO has not been configured to use the PFS file system"
     MPIR_ERR_NO_PIOFS "ROMIO has not been configured to use the PIOFS file system"
     MPIR_ERR_NO_UFS "ROMIO has not been configured to use the UFS file system"
@@ -52,6 +52,7 @@
     MPIR_ERR_NO_SFS "ROMIO has not been configured to use the SFS file system"
     MPIR_ERR_NO_PVFS "ROMIO has not been configured to use the PVFS file system"
     MPIR_ERR_NO_PANFS "ROMIO has not been configured to use the PANFS file system"
+    MPIR_ERR_NO_PLFS "ROMIO has not been configured to use the PLFS file system"
     MPIR_ERR_MULTIPLE_SPLIT_COLL "Only one active split collective I/O operation allowed per file handle"
     MPIR_ERR_NO_SPLIT_COLL "No previous split collective begin"
     MPIR_ERR_ASYNC_OUTSTANDING "There are outstanding nonblocking I/O operations on this file"
diff -Naur mpich2-1.2.1p1.ORIG/src/mpi/romio/adio/include/adioi_fs_proto.h mpich2-1.2.1p1/src/mpi/romio/adio/include/adioi_fs_proto.h
--- mpich2-1.2.1p1.ORIG/src/mpi/romio/adio/include/adioi_fs_proto.h	2008-08-14 12:46:36.000000000 -0600
+++ mpich2-1.2.1p1/src/mpi/romio/adio/include/adioi_fs_proto.h	2010-03-10 11:36:55.659338000 -0700
@@ -19,6 +19,11 @@
 /* prototypes are in adio/ad_panfs/ad_panfs.h */
 #endif
 
+#ifdef ROMIO_PLFS
+extern struct ADIOI_Fns_struct ADIO_PLFS_operations;
+/* prototypes are in adio/ad_plfs/ad_plfs.h */
+#endif
+
 #ifdef ROMIO_PFS
 extern struct ADIOI_Fns_struct ADIO_PFS_operations;
 /* prototypes are in adio/ad_pfs/ad_pfs.h */
diff -Naur mpich2-1.2.1p1.ORIG/src/mpi/romio/adio/include/mpio_error.h mpich2-1.2.1p1/src/mpi/romio/adio/include/mpio_error.h
--- mpich2-1.2.1p1.ORIG/src/mpi/romio/adio/include/mpio_error.h	2008-11-06 14:29:57.000000000 -0700
+++ mpich2-1.2.1p1/src/mpi/romio/adio/include/mpio_error.h	2010-03-10 11:40:44.142595000 -0700
@@ -52,6 +52,7 @@
 #define MPIR_ERR_NO_HFS 15
 #define MPIR_ERR_NO_XFS 17
 #define MPIR_ERR_NO_SFS 19
+#define MPIR_ERR_NO_PLFS 20
 #define MPIR_ERR_NO_PVFS 21
 #define MPIR_ERR_NO_PANFS 22
 #define MPIR_ERR_MULTIPLE_SPLIT_COLL 23
diff -Naur mpich2-1.2.1p1.ORIG/src/mpi/romio/adio/include/romioconf.h.in mpich2-1.2.1p1/src/mpi/romio/adio/include/romioconf.h.in
--- mpich2-1.2.1p1.ORIG/src/mpi/romio/adio/include/romioconf.h.in	2010-02-22 15:21:31.000000000 -0700
+++ mpich2-1.2.1p1/src/mpi/romio/adio/include/romioconf.h.in	2010-03-10 11:39:56.265482000 -0700
@@ -300,6 +300,9 @@
 /* Define for ROMIO with PANFS */
 #undef ROMIO_PANFS
 
+/* Define for ROMIO with PLFS */
+#undef ROMIO_PLFS
+
 /* Define for ROMIO with PFS */
 #undef ROMIO_PFS
 
diff -Naur mpich2-1.2.1p1.ORIG/src/mpi/romio/configure.in mpich2-1.2.1p1/src/mpi/romio/configure.in
--- mpich2-1.2.1p1.ORIG/src/mpi/romio/configure.in	2009-11-02 16:31:04.000000000 -0700
+++ mpich2-1.2.1p1/src/mpi/romio/configure.in	2010-03-10 11:24:22.482457000 -0700
@@ -100,7 +100,7 @@
 #
 have_aio=no
 #
-known_filesystems="nfs ufs pfs pvfs pvfs2 testfs xfs panfs gridftp lustre bgl bglockless zoidfs"
+known_filesystems="nfs ufs pfs pvfs pvfs2 testfs xfs panfs plfs gridftp lustre bgl bglockless zoidfs"
 known_mpi_impls="mpich2_mpi mpich_mpi sgi_mpi hp_mpi cray_mpi lam_mpi"
 #
 # Defaults
@@ -1110,6 +1110,9 @@
 if test -n "$file_system_panfs"; then
     AC_DEFINE(ROMIO_PANFS,1,[Define for ROMIO with PANFS])
 fi
+if test -n "$file_system_plfs"; then
+    AC_DEFINE(ROMIO_PLFS,1,[Define for ROMIO with PLFS])
+fi
 if test -n "$file_system_ufs"; then
     AC_DEFINE(ROMIO_UFS,1,[Define for ROMIO with UFS])
 fi
@@ -2183,6 +2186,7 @@
 		   adio/ad_bgl/Makefile \
 		   adio/ad_bglockless/Makefile \
 		   adio/ad_panfs/Makefile \
+		   adio/ad_plfs/Makefile \
 		   adio/ad_xfs/Makefile \
 		   adio/ad_sfs/Makefile adio/ad_pfs/Makefile \
 		   adio/ad_testfs/Makefile adio/ad_pvfs/Makefile \
diff -Naur mpich2-1.2.1p1.ORIG/src/mpi/romio/README mpich2-1.2.1p1/src/mpi/romio/README
--- mpich2-1.2.1p1.ORIG/src/mpi/romio/README	2008-03-10 16:16:20.000000000 -0600
+++ mpich2-1.2.1p1/src/mpi/romio/README	2010-03-10 11:25:37.113953000 -0700
@@ -1,5 +1,14 @@
           ROMIO: A High-Performance, Portable MPI-IO Implementation
 
+                      Version 2010-03-08
+
+Major Changes in this version:
+------------------------------
+* added PLFS support
+  http://sourceforge.net/projects/plfs/
+  http://institutes.lanl.gov/plfs/
+
+
                       Version 2008-03-09
 
 Major Changes in this version:
--- mpich2-1.2.1p1.ORIG/src/mpi/romio/Makefile.in	2009-09-17 07:56:10.000000000 -0600
+++ mpich2-1.2.1p1/src/mpi/romio/Makefile.in	2010-03-10 18:24:14.771333000 -0700
@@ -15,7 +15,7 @@
 MPIO_DIRS   = mpi-io
 EXTRA_SRC_DIRS = @EXTRA_SRC_DIRS@
 FILE_SYS_DIRS = @FILE_SYS_DIRS@
-ALL_DIRS    = mpi-io mpi-io/fortran mpi2-other/info mpi2-other/info/fortran mpi2-other/array mpi2-other/array/fortran adio/common adio/ad_pfs adio/ad_piofs adio/ad_nfs adio/ad_ufs adio/ad_xfs adio/ad_hfs adio/ad_sfs adio/ad_testfs adio/ad_pvfs adio/ad_pvfs2 adio/ad_panfs adio/ad_gridftp adio/ad_lustre adio/ad_bgl adio/ad_bglockless test test-internal mpi-io/glue/default mpi-io/glue/mpich1 mpi-io/glue/mpich2
+ALL_DIRS    = mpi-io mpi-io/fortran mpi2-other/info mpi2-other/info/fortran mpi2-other/array mpi2-other/array/fortran adio/common adio/ad_pfs adio/ad_piofs adio/ad_nfs adio/ad_ufs adio/ad_xfs adio/ad_hfs adio/ad_sfs adio/ad_testfs adio/ad_pvfs adio/ad_pvfs2 adio/ad_plfs adio/ad_panfs adio/ad_gridftp adio/ad_lustre adio/ad_bgl adio/ad_bglockless test test-internal mpi-io/glue/default mpi-io/glue/mpich1 mpi-io/glue/mpich2
 SHELL       = /bin/sh
 
 @VPATH@