To maintain a constant connection between an ESX host and its storage, ESX supports multipathing. Multipathing is a technique that lets you use more than one physical path for transferring data between the ESX host and the external storage device.

In case of a failure of an element in the SAN network, such as an HBA, switch, or cable, ESX can use alternate physical paths to access a storage device. This process is known as path failover. In addition to path failover, multipathing offers load balancing, which redistributes I/O loads between multiple paths, thus reducing or removing potential bottlenecks.