Choose Shut down or Restart.
For a clustered controller system, you can choose Restart in Sequence or Restart Simultaneously. Restart in Sequence does not cause a system outage. Storage Center shuts down the first controller, and then restarts the first controller. When the first controller is up, Storage Center shuts down and restarts the second controller. Ports will be unbalanced and Storage Center will ask you to re-balance the ports.
For a clustered controller system, Restart Simultaneously shuts both controllers down simultaneously and then brings them back on line. This causes a system outage. When the controllers are restarted, they may or may not be unbalanced.