"Schlottke-Lakemper, Michael" <m.schlottke-lakem...@aia.rwth-aachen.de> writes:
> Hi Dave, > >> That's probably not a good idea. Have you read about NFS in the romio >> README? It's old, but as far as I know, it's still relevant for NFS3. >> Maybe Rob Latham will see this and be able to comment on NFS4. > No, are you referring to the file > openmpi-1.8.7/ompi/mca/io/romio/romio/README? The only hint they give > is that they suggest to use the “noac” option, which according to the > manpages should not affect file contents but rather file attributes > only (if I understand it correctly). Or do you think it would still be > worth trying? By the way, we are using NFSv3. As far as I remember, you need "noac" and "sync", but I've never tried. We couldn't afford to run with the relevant options anyway after it emerged there was requirement for MPI-IO on a new system here. It was just a warning about NFS in general before an expert speaks up, and I'm surprised it worked OK previously. >> It seems to me that building for NFS by default is a mistake. > Can you tell me the correct flags I need to provide at configure-time? I think the romio flags are fairly obvious from ./configure --help=recursive but I doubt that would help unless you have a parallel filesystem available. (You can set up orangefs on the fly on compute node local disks and copy results off at the end of a job, if that's any help.) I meant that I think you should have to configure NFS explicitly, with a warning. Having it as a default gives the impression it will just work. I _think_ the default is or was "ufs,nfs" -- apologies if I mis-remember. > Or where I can find more information about that (there does not seem > to be anything about configure flags in the above-mentioned > README). Also, as Gilles (see other mail in thread) suggested, I am > not sure whether we use romio or ompio, but I do not know how to find > out. ompio in 1.8 only has pvfs2 (== orangefs) and ufs support -- which might be a good reason to use pvfs2. You'll need an expert to say if you can use ufs correctly over an nfs filesystem. (I assume you are actually picking up the romio nfs support.)
