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Because DRS cannot migrate controller VMs, PowerStore X model appliances include the Maintenance Mode Service (MMS), which manages the controller VMs during maintenance mode operations. Instead of being moved, the controller VM is gracefully powered off.
Before shutting down or rebooting a PowerStore X model ESXi node, put the node into maintenance mode first. Entering maintenance mode ensures that there are no VMs running on this node before it is shut down or rebooted. When maintenance mode is entered, DRS migrates any running VMs to the peer node in the vSphere cluster. The following figure shows the maintenance mode operations that are available in vCenter:
If maintenance mode is initiated on a PowerStore X model ESXi node, MMS automatically initiates a shutdown of the node controller VM. The shutdown of the controller VM is started after the migration of all the user VMs has completed. After the controller VM successfully powers off, the ESXi node enters maintenance mode. When maintenance mode is entered, the ESXi node can be rebooted or shut down from vCenter without impact.
When one of the controller VMs is powered off or rebooted, the services fail over to the other controller VM. To avoid interruption, place only a single node of an appliance in maintenance mode at a time. To restore high availability, maintenance mode must be exited on the node. When the administrator initiates an exit maintenance mode operation, MMS automatically powers up the controller VM. When the controller VM fully powers up, controller VM redundancy is restored.
After entering or exiting maintenance mode on a PowerStore X model ESXI node, wait a few minutes before issuing another maintenance mode operation. This period provides the controller VMs enough time to completely fail over all resources and services before starting the next operation.