Overriding the migration policy
You can override the migration policy for a given VM after allocating cache to it. The cache allocation for the VM remains the same until you change it explicitly.
Steps 
1.
From the VM Inventory page of the FAMC, click the wrench icon for the VM and select Advanced > Migration.
2.
In the migration dialog box, click Enable Migration, then select each migration target host. You will receive an error message if a selected host has less available cache than has been allocated to the VM.
Note: Use the links in the Refine Policy area to specify a cluster or datacenter scope.
Parent Topic: Preparing for vMotion migration