FAQ:
Running jobs under BProc

Table of contents:

1. What versions of BProc does Open MPI work with?
2. What pre-requisites are necessary for running an Open MPI job under BProc?

As of December 2005, Open MPI supports recent versions of BProc, such as those found in Clustermatic. We have not tested with older forks of the BProc project, such as those from Scyld. Since Open MPI's BProc support uses some advanced support from recent BProc versions, it is somewhat doubtful (but totally untested) as to whether it would work on Scyld systems.

Feedback and/or assistance to getting Open MPI to run properly on Scyld systems would be greatly appreciated.

In general, they are the same for running Open MPI jobs in other environments (see this FAQ category for more general information).

However, BProc it is worth noting that BProc may not bring all necessary dynamic libraries with a process when it is migrated to a back-end compute node. Plus, Open MPI opens components on the fly (i.e., after the process has started), so if these components are unavailable on the back-end compute nodes, Open MPI applications may fail.

In general the Open MPI team recomends one of the following two solutions when running on BProc clusters (in order):

1. Compile Open MPI statically, meaning that Open MPI's libraries produce static ".a" libraries and all components are included in the library (as opposed to dynamic ".so" libraries, and separate ".so" files for each component that are found and loaded at run-time) so that applications do not need to find any shared libraries or components when they are migrated to back-end compute nodes. This can be accomplished by specifying --enable-static --disable-shared to configure script when building Open MPI.
2. If you do not wish to use static compilation, ensure that Open MPI is fully installed on all nodes (i.e., the head node and all compute nodes) in the same directory location. For example, if Open MPI is installed in /opt/openmpi-1.6.4 on the head node, ensure that it is also installed in that same directory on all the compute nodes.