How can I send a job to a specific machine?
You can use one of the predefined hardware properties that unambiguously identify a hardware type (see column Property of the hardware table). This property can be used to run a job on a specific hardware type.
Example 1: to submit a job on a single Sun x2250:
qsub -l nodes=1:x2250 myjob.sh
Example 2: to submit a job on a single HP BL 460c and ensuring that only this job will run on this machine by requesting all of its processors.
qsub -l nodes=1:blm620:ppn=4 myjob.sh