Sent to CCL by: Justin Finnerty [justin.finnerty\a/]
 On Wed, 2008-11-12 at 07:14 -0500, John McKelvey
 > Folks,
 > I am a newbie as to running parallel under linux, and need to install
 > MPI under RHEL4/AMD-64bit.
 > Simple question: Where to start?
 I would add that it depends on what you want to do. If you are only
 writing your own MPI code then look at OpenMPI as it comes with an RPM
 specfile for building a set of RPMs. This makes it much easier to manage
 in the long-term.
 However, while MPI implementations are supposed to be source compatible
 they are not object compatible. What this means is that you will have to
 install the matching MPI library for each software you use. For example
 we have had to install LAM MPI, OpenMPI, MPICH and MPICH2 on our cluster
 to support the computational chemistry software we use (eg NWChem, ORCA
 etc). (I also strongly recommend the OSC mpiexec program for MPICH and
 Four MPI installations provides a major problem with configuring your
 user environment as you can only have _one_ MPI implementation
 configured at a time. We solved this using the Modules program, which
 allows us to load and unload settings for each MPI and disallows loading
 of two simultaneously. You can also use it to configure your chemistry
 software, which can then load the required MPI module. (The Modules
 program should be part of RHEL4 installation.)
 Dr Justin Finnerty
 Rm W3-1-165         Ph 49 (441) 798 3726
 Carl von Ossietzky Universität Oldenburg