Hi, At Cray, we have a a Cluster Compatibility Mode (CCM) which runs under PBSPro. If we do a qsub, we get an allocation of compute nodes and the first node in the list of allocated nodes is considered the "head node" of the "Cluster".
The list of allocated nodes is contained in the file $PBS_NODEFILE. To launch a command on the head node we type: ccmrun COMMAND In the normal PBSPro environment, we launch the OpenMPI mpirun as: ccmrun ${OpenMPI_Install}/bin/mpirun <options ..> -hostfile host.list -np $NCPUS ./hello_mpi This all works great with the "mpirun" command launching on the "head node" and the the mpirun command using ssh/rsh to launch other processes on the other nodes in the virtual cluster. Everything works. On Cray sites, that use PBSPro/Torque/Moab, OpenMPI detects that Torque/Moab is present and attempts to use Torque/Moab to launch on other nodes. Because of the way Cray has Torque/moab configured, this doesn't work. This is not a problem with OpenMPI. Is there an option to OpenMPI to tell it to ignore Torque/Moab and use rsh/ssh and the -hostfile/hosts even if Torque/Moab is detected?? I've looked through the README and the FAQ but I haven't seen anything. Many thanks, Dave -- CCCCCCCCCCCCCCCCCCCCCCFFFFFFFFFFFFFFFFFFFFFFFFFDDDDDDDDDDDDDDDDDDDDD David Whitaker, Ph.D. whita...@cray.com Aerospace CFD Specialist phone: (651)605-9078 ISV Applications/Cray Inc fax: (651)605-9001 CCCCCCCCCCCCCCCCCCCCCCFFFFFFFFFFFFFFFFFFFFFFFFFDDDDDDDDDDDDDDDDDDDDD