[sylvester]

Recently we updated our compute cluster from CentOS 5.5 to Debian 7, mostly because we had trouble compiling OpenFOAM 2.2.x with the GCC version available.

However, we are now seeing a large drop-off in performance, but only for cases running OF-2.2.x; OF-2.1.x performs, roughly, as before. We suspect there is a communication problem between the nodes, as jobs using only one (multi-cpu, multi-core) node do not show this behaviour. Gigabit ethernet is used for the interconnect.

Is anyone else experiencing this?

Thanks,
Sylvester

ps. For both OF versions the system GCC was used (version 4.7.2) and the third party openmpi (version 1.5.3 for OF-2.1.x and version 1.6.3 for OF-2.2.x). No changes were made to any OpenFOAM settings or compile flags.