It is possible that it becomes necessary to disable the DRS (Distributed Resource Scheduler) feature on an ESX cluster. A typical scenario would be maintenance on your ESX hosts./VirtualCenter. This avoids that virtual machines will VMotion to another host. You must be very careful: when disabling (unchecking) DRS as a cluster option in VirtualCenter all resource pools for that cluster will be deleted. Just set DRS to manual to avoid this and set DRS back to fully automated after the maintenance period is over
