Along came another users with a requirement for MPI. Can we run it? Well yes you can but remember our interconnects are just plain old Ethernet and nothing fancy like Myrinet or Infiniband. We are not a HPC cluster but an HTC cluster.
So we have been building CASTEP, an f90 code, heavy on the MPI scatter/gather. A test of true grid for any HTC cluster. First off CASTEP requires a minimum of make3.81 and gfortran43. Handy that we moved to SL5 as these are now the standard. Coupled with making sure that the required libs fftw3, blas and lapack are all built with the same compiler, gfortran43. This allowed the single core version to be built and installed onto the grid.
An MPI version is turning out be a bit more work. First off the old, outdated and no longer developed libs MPICH have not been built with .f90 support enabled by default. So we have got hold of the source to do a recompile with .f90 support on for gfortran43. There also appeared to be a bug in the gfortran support. So we had to patch the src rpm to include a patch that we located online. This allowed us to finally build the mpich lib. This has been tested with compilation of an MPI job in c and f90, both of which run successfully.
Unfortunately CASTEP still doesn't run using it so more digging required.