When transferring data between the host server and storage, the SAN uses a multipathing technique. Multipathing allows you to have more than one physical path from the ESX/ESXi host to a LUN on a storage system.

If a path or any component along the path, HBA or NIC, cable, switch or switch port, or storage processor, fails, the server selects another of the available paths. The process of detecting a failed path and switching to another is called path failover.