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Subject: [OMPI users] Info needed for building Open-MPI against external ROMIO
From: David Gunter (dog_at_[hidden])
Date: 2008-02-11 16:33:21

We have a number of patches and files to be added to ROMIO to make it
work with recent releases of the Panasas file system. We have reached
a point where the stock ROMIO included in Open-MPI no longer works for
what we need. I know that the version of ROMIO forged into the bowels
of OMPI is a beast to try and patch or mend so that is something we
won't attempt.

Thus we have two choices here at LANL. Either we drop support and no
longer provide OMPI to our user community and switch to MVAPICH2 for
our only MPI on systems, or we can try and build OMPI against an
externally maintained ROMIO.

In an August 2007 email Jeff Squyres hinted that there is a way to do
the latter:

| Continual re-integration of ROMIO is definitely a logistics problem
| that we have not solved. And it's becoming a bigger problem. :-(
| Normally, we're quite open to accepting patches to Open MPI to put
| them into the main distribution to ease the whole "millions of MPI
| distros" issue, but with ROMIO it becomes quite difficult because we
| have to source from Argonne's copy. Trying to manage what patches
| need to go in is already quite difficult because:
| - ROMIO is not on our release schedule
| - OMPI adds its own integration patches to ROMIO
| - All the OMPI developers have other work to do ;-)
| Adding 3rd party patches in there for something that we already know
| is complex and understaffed has unfortunately been a low priority. :-(
| One thing that may make things a little better is that Brian recently
| integrated some work onto the OMPI trunk that allows ROMIO to be
| built outside of OMPI. Hence, if you have a standalone ROMIO, OMPI
| can use it. I don't know the details (i.e., if you can still use
| mpi.h / MPI_Request / MPI_Test / MPI_Wait like you can with the
| default OMPI ROMIO integration) -- Brian will have to chime in here...
| So I don't know what the real solution is here -- I'm just trying to
| give some of the OMPI perspective. Suggestions are welcome.
| Probably the best solution would be someone to volunteer to actually
| spend the cycles to maintain ROMIO in Open MPI (I am pretty sure that
| Brian simply does not have them)...
| --
| Jeff Squyres
| Cisco Systems

Since Brian no longer works on these issues I'm wondering if and how
it is possible.


David Gunter
HPC-3: Parallel Tools Team
Los Alamos National Laboraotry