[Pw_forum] Restarting PWSCF - usability issues
francesco.antoniella at aquila.infn.it
Wed Mar 10 13:45:41 CET 2004
> For machines having a parallel file system (i.e. the sp4 in
> Cineca, Bologna), the problem is not that serious: all files
> are in the same place, and the I/O is still very fast (or at
> least, that is what I understood). Trouble arises only if you
> want to restart with a different number of processors .
> For machines without a parallel file system (i.e. the sp3 in
> PMI, Princeton) your *wfc files are scattered on different file
> systems in different processors (forget using I/O via NFS!).
> Restarting is a mess: you need a copy of all files on all
> processors, since there is no way to tell which physical
> processor corresponds to which logical one in MPI.
For a PC cluster a good workaround is to use the openmosix package and
its MFS see-all-the-disks filesystems.
I implemented it in the Attila cluster at L'Aquila university at permits
a quite fast writing via network (better than NFS) and/or accessibility
of the nodes' filesystems in a reasonnably simple way.
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