san(修改中)

A SAN is ahigh-speed network that allows the establishment of direct connections between
storage devices and processors (servers) within the distance supported by Fibre
Channel. 

The SAN can be viewed as an extension to the storage bus concept, which
enables storage devices and servers to be interconnected using similar elements
as in local area networks (LANs) and wide area networks (WANs): routers, hubs,switches, directors, and gateways. A SAN can be shared between servers and/or
dedicated to one server. It can be local, or can be extended over geographical
distances.