With RHEL6.6, mpich2 has been replaced with mpich-3.1 and openmpi-1.5.4 has been replaced with openmpi 1.8.1. These are incompatible upgrades and have broken dependencies on a number of EPEL packages that provide mpich and openmpi versions. These packages are in the process of being rebuilt and will hopefully be at least in epel-testing soon. This will cause ongoing issues for users of these packages that wish to remain on earlier versions of SL6, but I'm afraid not much can be done about it at this point. -- Orion Poplawski Technical Manager 303-415-9701 x222 NWRA, Boulder/CoRA Office FAX: 303-415-9702 3380 Mitchell Lane [log in to unmask] Boulder, CO 80301 http://www.nwra.com