You can use the PREEMPTPOLICY parameter to control how the scheduler preempts a job. This parameter enforces preemption using one of the following methods:

PREEMPTPOLICY type	Description
SUSPEND	Causes active jobs to stop executing, but to remain in memory on the allocated compute nodes.
CHECKPOINT	Saves the current job state and either terminates or continues running the job. A checkpointed job may restart at any time and resume execution from its most recent checkpoint.
REQUEUE	Terminates active jobs and returns them to the job queue in an idle state.
CANCEL	Cancels active jobs.

Each of these methods vary in the level of disruption to the job, SUSPEND being the least disruptive and CANCEL being the most disruptive.

Moab uses preemption escalation to free up resources. So for example, if the PREEMPTPOLICY is set to SUSPEND, Moab uses this method if it is available; however, it Moab will escalate to something potentially more disruptive if necessary to preempt and free up resources.

The following sections include information about each PREEMPTPOLICY type, their different usage benefits, and any additional configurations and settings needed to use them.

• Using SUSPEND
• Using CHECKPOINT
• Using REQUEUE
• Using CANCEL