shutdown procedure for data center

Hi All, Due to some power issue we will be shutting down entire data center for 8 hours. I searched but couldnt find anything about shutting down celerra and data domain. Can someone help with the shutting down and start up procedure or point me to right direction. Thank you

critical list of equipment's

VNX 5400

EMC data domain 2500

Vmware ESX host running

Quantum tape library

netback up server.