Dear List,
I'm facing a problem with the mpi-io on pvfs.
I'm using orangefs-2.8.7 on 6 server nodes.
I recently tried to play with mpi-io as pvfs is designed to
support parallel access to a single file.
I used the following simple code (see below) where different processes
open a file
and write each at a different position in the file.
I compiled it with mpich2, as pvfs seems to only support this version to
use the
parallel access facilities, right ?
When running my test code on a classical file system, the code works
perfectly and I get the following output:
/mpirun -n 4 ./a.out
PE03: write at offset = 30
PE03: write count = 10
PE00: write at offset = 0
PE00: write count = 10
PE01: write at offset = 10
PE01: write count = 10
PE02: write at offset = 20
PE02: write count = 10
/
as expected a file "testfile" is created.
However, the same code acessing my pvfs file system gives:
/mpirun -n 4 ./a.out
PE00: write at offset = 0
PE00: write count = -68457862
PE02: write at offset = 20
PE02: write count = 32951150
PE01: write at offset = 10
PE01: write count = -110085322
PE03: write at offset = 30
PE03: write count = -268114218/
and no file "testfile" is created.
I'm I doing something wrong ? Do I need to compile orangefs or mpich2 with
particular options ?
Thanks for your precious help,
yves
My simple code:
---------------------
#include "mpi.h"
#include <stdio.h>
#define BUFSIZE 10
int main(int argc, char *argv[])
{
int i, me, buf[BUFSIZE];
int b, offset, count;
MPI_File myfile;
MPI_Offset disp;
MPI_Status stat;
MPI_Init(&argc, &argv);
MPI_Comm_rank(MPI_COMM_WORLD, &me);
for (i=0; i<BUFSIZE; i++)
buf[i] = me*BUFSIZE + i;
MPI_File_open(MPI_COMM_WORLD, "testfile", MPI_MODE_WRONLY |
MPI_MODE_CREATE,
MPI_INFO_NULL, &myfile);
offset = 0;
b = BUFSIZE;
MPI_Exscan(&b, &offset, 1, MPI_INT, MPI_SUM,MPI_COMM_WORLD);
disp = offset*sizeof(int);
printf("PE%2.2i: write at offset = %d\n", me, offset);
MPI_File_set_view(myfile, disp,
MPI_INT, MPI_INT, "native", MPI_INFO_NULL);
MPI_File_write(myfile, buf, BUFSIZE, MPI_INT,
&stat);
MPI_Get_count(&stat, MPI_INT, &count);
printf("PE%2.2i: write count = %d\n", me, count);
MPI_File_close(&myfile);
MPI_Finalize();
return 0;
}
--
---------------------------------------------------------------------
Dr. Yves Revaz
Laboratory of Astrophysics
Ecole Polytechnique Fédérale de Lausanne (EPFL)
Observatoire de Sauverny Tel : +41 22 379 24 28
51. Ch. des Maillettes Fax : +41 22 379 22 05
1290 Sauverny e-mail : [email protected]
SWITZERLAND Web : http://people.epfl.ch/yves.revaz
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