[mpich-discuss] ROMIO filesystem check during MPI_File_open

[Jeff Squyres (jsquyres)]

On Mar 14, 2014, at 11:23 AM, Rob Latham <robl at mcs.anl.gov> wrote:

> I thought we handled this?  we certianly seem to have made an effort:
> 
> https://trac.mpich.org/projects/mpich/browser/src/mpi/romio/adio/common/ad_fstype.c#L644

Sorry for the delay in getting back to this...

It looks like ADIO_FileSysType_fncall() is *not* collective -- it just does some magic to figure out what the local filesystem type is.  Then back up in ADIO_ResolveFileType(), since have_nfs_enabled==1 and ADIO_FileSysType_fncall() returned MPI_SUCCESS, MPI_Allreduce() is *not* called, and each process just proceeds with their local value for file_system.  That's where things go downhill: one process will get UFS, the rest will get NFS.

-- 
Jeff Squyres
jsquyres at cisco.com
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