[SCore-users-jp] Re: [SCore-users] MPI-IO

[Atsushi HORI]

Hi, Nick,

>Hi Score team. We seem to be having an MPI-IO problem with Score 5.4 x86 
>RedHat 7.3.
>The users files are NFS mounted from the front end (RedHat 7.3 x86)

I am not familiar with MPI-IO at all, but as far as I undestand, 
MPI-IO on NFS is not recommended. I found MPICH web page 
<http://www-unix.mcs.anl.gov/mpi/mpich/buglist-tbl.html>, and it says, 

---
Problems with MPI-IO and NFS
The network file system (NFS) must be configured extremely carefully 
for MPI-IO (and many other programs) to work correctly. 
Unfortunately, few systems are so configured, and doing so can 
adversely impact performance. As a result, programs using files on an 
NFS system may hang or produce incorrect results. Note that this is, 
officially, a design feature of NFS; unless the NFS system is 
configured with no attribute caching, any two processes, accessing 
the same file, may produce incorrect results. You can use the 
-file_system=ufs option of configure to build an MPICH that supports 
only UFS (Unix File System); MPI-IO works correctly with UFS, XFS, 
PIOFS, HFS, SFS, etc. (more precisely, those file system that 
correctly implement basic Unix I/O system calls; something that NFS 
does not do).


----
Atsushi HORI
Swimmy Software, Inc.

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