You can use event-based alarms in vCenter Server to monitor vSphere DPM.

The most serious potential error you face when using vSphere DPM is the failure of a host to exit standby mode when its capacity is needed by the DRS cluster. You can monitor for instances when this error occurs by using the preconfigured Exit Standby Error alarm in vCenter Server. If vSphere DPM cannot bring a host out of standby mode (vCenter Server event DrsExitStandbyModeFailedEvent), you can configure this alarm to send an alert email to the administrator or to send notification using an SNMP trap. By default, this alarm is cleared after vCenter Server is able to successfully connect to that host.

To monitor vSphere DPM activity, you can also create alarms for the following vCenter Server events.
Table 1. vCenter Server Events
Event Type Event Name
Entering Standby mode (about to power off host) DrsEnteringStandbyModeEvent
Successfully entered Standby mode (host power off succeeded) DrsEnteredStandbyModeEvent
Exiting Standby mode (about to power on the host) DrsExitingStandbyModeEvent
Successfully exited Standby mode (power on succeeded) DrsExitedStandbyModeEvent

For more information about creating and editing alarms, see the vSphere Monitoring and Performance documentation.

If you use monitoring software other than vCenter Server, and that software triggers alarms when physical hosts are powered off unexpectedly, you might have a situation where false alarms are generated when vSphere DPM places a host into standby mode. If you do not want to receive such alarms, work with your vendor to deploy a version of the monitoring software that is integrated with vCenter Server. You could also use vCenter Server itself as your monitoring solution, because starting with vSphere 4.x, it is inherently aware of vSphere DPM and does not trigger these false alarms.