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Subject: [OMPI devel] Error while writing more than 2GB data at once to file
From: Markus Wittmann (Markus.Wittmann_at_[hidden])
Date: 2009-09-10 09:33:40

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Hello,

at RRZE we tried to write > 2 GB data (per process) at once to a file
with MPI_File_write_at(_all). Thereby the function returns with error
code 35.

Attached you will find the compressed output of "ompi_info --all" and a
test program (large_mpi_test.F90) with that the problem can be
reproduced.

The Open MPI Vesion used was 1.3.3. The underlaying file system used is
Lustre which is able to deal with files > 2GB.

Further if we retrieve the file size with MPI_File_get_size for a file
>= 2 GB the returned size is negative. The attached test program
get_file_size.f90 will demonstrate the behavior:

$ dd if=/dev/zero of=delme.dat bs=1K count=1M
1048576+0 records in
1048576+0 records out
1073741824 bytes (1.1 GB) copied, 9.1401 seconds, 117 MB/s
$ mpirun -n 1 get_file_size
file size of delme.dat:
[0] file size = 1073741824 bytes, 0.102E+04 MB

$ dd if=/dev/zero of=delme.dat bs=1K count=2M
2097152+0 records in
2097152+0 records out
2147483648 bytes (2.1 GB) copied, 18.1567 seconds, 118 MB/s
$ mpirun -n 1 get_file_size
file size of delme.dat:
[0] file size = -2147483648 bytes, -.205E+04 MB

Regards
Markus Wittmann

• application/x-gzip attachment: ompi_info.log.tar.gz

• text/x-fortran attachment: large_mpi_test.F90

• text/x-fortran attachment: get_file_size.f90

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