In a simple multipathing local storage topology, you can use one ESX host, which has two HBAs. The ESX host connects to a dual-port local storage system through two cables. This configuration ensures fault tolerance if one of the connection elements between the ESX host and the local storage system fails.

To support path switching with FC SAN, the ESX host typically has two or more HBAs available from which the storage array can be reached using one or more switches. Alternatively, the setup can include one HBA and two storage processors so that the HBA can use a different path to reach the disk array.

In Fibre Channel Multipathing, multiple paths connect each server with the storage device. For example, if HBA1 or the link between HBA1 and the switch fails, HBA2 takes over and provides the connection between the server and the switch. The process of one HBA taking over for another is called HBA failover.

Fibre Channel Multipathing
The image shows multiple paths connecting each server with the storage device.

Similarly, if SP1 or the link between SP1 and the switch breaks, SP2 takes over and provides the connection between the switch and the storage device. This process is called SP failover. ESX supports HBA and SP failover with its multipathing capability.