[mvapich-discuss] open non-existing files on Lustre expecting MPI_ERR_NO_SUCH_FILE but got MPI_SUCCESS

[Wei-keng Liao]

Hi,

I am a developer of PnetCDF library and would like to file a bug report.
Mark Dixon, a PnetCDF user cc-ed in this email, reported an error when
building PnetCDF with mvapich2-2.2. The root cause of the error is due to
mvapich2-2.2 fails to return the expected MPI error class MPI_ERR_NO_SUCH_FILE
when a test program tries to open a non-existing file on Lustre.

After some diggings, I found out that the Lustre driver in mvapich2 appends
O_CREAT flag to the mode argument of the open call, (line 50, in file
src/mpi/romio/adio/ad_lustre/ad_lustre_open.c). Because of that, the file is
mistakenly created and MPI_SUCCESS is returned, which is an unexpected outcome
by MPI standard.

Attached is a small MPI program to reproduce such error. Mark has used it to
verify the issue described above. He also ran it against an ext4 (UFS) and the
correct error class was returned. So the problem is specific for Lustre driver.
Please see the discussion email threads:
http://lists.mcs.anl.gov/pipermail/parallel-netcdf/2017-February/001897.html


Wei-keng

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