Stands for "Storage Area Network."
A SAN is a specialized network of storage devices accessible by multiple servers or workstations. A SAN is a separate network from a LAN, with access between the two typically managed by file servers that connect to both networks and create a bridge. A file server sees the SAN storage pool as if it were a local disk connected directly to the server, and it can share that storage with the rest of the LAN. SANs are used by enterprises and other large organizations that need large pools of high-speed, low-latency network data storage.
A file server can only connect to as many drives as it has physical interfaces for, so a SAN can provide more data storage capacity than a single file server could provide. Storage devices in a SAN are connected using high-speed Fibre Channel connections and managed by SAN switches. A file server equipped with a Fibre Channel interface can connect to a SAN switch and access its storage pool. Multiple file servers can independently connect to the same SAN to provide network administrators with more options for managing data access.
Unlike a NAS or traditional network storage drive, a SAN stores data using block-level storage that manages and organizes data in fixed-sized blocks instead of by entire files. Block-level storage can provide higher data access speeds and lower latency by spreading files out across multiple physical drives. For example, if a SAN saves a 5 GB data file in blocks on five separate drives, each one only needs to read 1 GB of data — providing much quicker access than if one drive had to read all 5 GB by itself.
In most cases, access to a SAN storage pool is provided by a file server acting as a bridge. However, sometimes it may be beneficial for a workstation to connect to a SAN directly and bypass any overhead from a file server. For example, a video editing workstation that requires high-speed access to large 8K video files can use a Fibre Channel interface to connect directly to a SAN storage pool for the fastest possible access speed.