The cluster has a module that sets a parallel environment. This module can also be used as a way to 'reserve' slots in a desired queue.

To load the module, simply type:

module load openmpi

Now, when we submit a job that will require more than one CPU/slot, either with qsub or qlogin, we can add the following parameter:

qsub -pe openmpi N ...

Where N is the number of CPU/slots we would like to use for that job. The cluster will assign N slots to run. You can combine the -l hostname=HNAME parameter to ensure that those slots will be used on a single node if you want. Otherwise, openmpi will distribute the reserved slots across all nodes.