For those who like to interact with their cluster jobs, it could not be easier. Instead of using the qsub command, just use:

qlogin -q ttn.q [options]

It's that easy. Qlogin will create an interactive session attached to the specified queue. You can play around as much as you want as in a normal session. You can also specify all options seen so far for qsub (-l hostname=HNAME, -pe openmpi N, -N NAME, etc…).

Using interactive sessions instead of normal sessions is crucial to ensure the good performance of the cluster. For instance, by specifying the number of CPU/slots that the session will require and a node name, you will prevent other jobs to be assigned to the node in which the interactive session is running. So say that cronus has 64 free slots, and we create an interactive session that will use 12 slots (in which we will run a matlab instance with matlabpool). Then, there will be 52 nodes availables for that node that other jobs will use. Note that if we ran a matlabpool session in a normal terminal, no slots would be reserved and hence 64 other jobs could run in that same node.

If we want to create an interactive session that will use more than one CPU, the following example should do the work:

qlogin -q ttn.q -pe smp 12

The first line will create the appropriate parallel environment. The qlogin statement will create an interactive session in the best available node, requesting 12 CPU's.