Storage Area Network (SAN) allows hosts, like a server, to access remote network storage as opposed to storage that is directly attached (aka DAS for direct attached storage).
A host’s boot up operating system boot partition can actually be on the SAN and does not necessarily need to be stored locally on the locally attached storage.
With a SAN you usually have a dedicated network specifically for disk I/O traffic over the network. This can be in the form of a Fibre Channel (FC), Fibre Channel over Ethernet (FCoE) or iSCSI.
