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Subject: Re: [OMPI users] How to set up state-less node /tmp for OpenMPI usage
From: Jeff Squyres (jsquyres_at_[hidden])
Date: 2011-11-03 12:35:16

On Nov 1, 2011, at 7:31 PM, Blosch, Edwin L wrote:

> I’m getting this message below which is observing correctly that /tmp is NFS-mounted. But there is no other directory which has user or group write permissions. So I think I’m kind of stuck, and it sounds like a serious issue.

That does kinda suck. :-\

> Before I ask the administrators to change their image, i.e. mount this partition under /work instead of /tmp, I’d like to ask if anyone is using OpenMPI on a state-less cluster, and are there any gotchas with regards to performance of OpenMPI, i.e. like handling of /tmp, that one would need to know?

I don't have much empirical information here -- I know that some people have done this (make /tmp be NFS-mounted). I think there are at least some issues with this, though -- many applications believe that a sufficient condition for uniqueness in /tmp is to simply append your PID to a filename. But this may no longer be true if /tmp is shared across multiple OS instances.

I don't have a specific case where this is problematic, but it's not a large stretch to imagine that this could happen in practice with random applications that make temp files in /tmp.

Jeff Squyres
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