The Set CPU action in vRealize Operations Manager modifies the number of vCPUs on a virtual machine. You increase the number of CPUs to address performance problems or decrease the number of CPU to reclaim resources.

The Set CPU Count action shuts down or powers off the target virtual machines, which is required if you are decreasing the CPU count, creates a snapshot if requested, changes the number of vCPUs based on the new CPU count you provided, and returns the virtual machines their original power states.

If Hot Plug is enabled on the virtual machines, then power off is not required. If power off is required and VM Tools are installed, then the virtual machines are shut down before they are powered off.

For the supported objects and object levels, this action is available in the following locations in vRealize Operations Manager:

Center pane Action menu.

List toolbars, including Views on the Details tab, List on the Environments tab.

Resource List and Topology Graph dashboard widgets.

Environment Overview list. In the left pane, click the Administration icon, and click List.

Configured alert recommendations.

Review the following information about the virtual machines to ensure that you are submitting the action for the correct objects.



Selected objects

Check box indicates whether the action is applied to the object. If you do not want to run the action on one or more objects, deselect the associated check boxes. This option is available when two or more objects are selected.

If you modify a value, the check box is selected. The check box must be selected to enable the OK button.


Name of the virtual machine as it appears in the environment inventory.


Number of CPUs when the action is completed. If the value is less than 1 or a value not supported for the virtual machine in vCenter Server, and the virtual machine is powered on and Hot Add is not enabled, the number of CPUs does not change and Recent Tasks shows the action as failed. If the virtual machine is powered off when you submit an unsupported value, the task reports success, but the virtual machine will fail when you run a power on action.

The value that appears is the calculated recommended size. If the target virtual machine is new or offline, this value is the current number of CPUs. If vRealize Operations Manager has been monitoring the virtual machine for 6 or more hours, depending on your environment, the value that appears is the CPU Recommended Size metric.

Current CPU

Number of configured CPUs.

Power State

Indicates whether the virtual machine is powered on or powered off.

Power Off Allowed

If selected, the action shuts down or powers off the virtual machine before modifying the value. If VMware Tools is installed and running, the virtual machine is shut down. If VMware Tools is not installed or not running, the virtual machine is powered off without regard for the state of the operating system.

In addition to whether the action shuts down or powers off a virtual machine, you must consider whether the object is powered on and what settings are applied.

See Working With Actions That Use Power Off Allowed.


Creates a snapshot before changing the number of CPUs. Use this option if you need a snapshot to which you can revert the virtual machine if the action does not produce the expected results.

The name of the snapshot is supplied in the Recent Tasks messages for the action.

If the CPU is changed with CPU Hot Plug enabled, then the snapshot is taken with the virtual machine is running, which consumes more disk space.


Name of the host on which the virtual machine is running.

Adapter Instance

Name of the VMware Adapter as it is configured in vRealize Operations Manager. The adapter manages the communication with the vCenter Server instance.

After you click OK, the next dialog box provides the task ID and a link to the task list.

Task ID Dialog Box



Recent Tasks

To view the status of the job and verify that the job finished, click Recent Tasks.


To close the dialog box without further action, click OK.