To configure a proper highly available SAN failover configuration with EMC storage models equipped with two storage processors, each ESX Server must have:
Two Fibre Channel host bus adapters (HBAs), such as QLogic or Emulex.
Two fibre switches.
Two storage processors (SPs): SPA and SPB. Each storage processor must have at least two ports connected to the SAN.
Use the following connection settings:
HBA0 and HBA1 on each ESX Server connected to switches 1 and 2, respectively.
Switch 1 connected to port 1 on SPA and port 2 on SPB. Switch 2 connected to port 2 on SPA and port 1 on SPB. Make sure to connect SPA ports to the lower switch port number compared to SPB ports. This allows SPA ports to be on the first paths seen by the host bus adapters in ESX Servers.
This configuration provides two paths from each HBA. The order of the paths in the above configuration provides HBA and switch failover without the need to trigger Auto-Volume Transfer (AVT). LUNs must be owned by the storage processor to which the preferred and active paths are connected (in the above configuration, they should be owned by SPA). Please note that the above assumes that the switches are not connected via Inter-Switch Link (ISL) in one fabric.