Storage area network

A Storage Area Network (SAN) in computing is a network which is designed to attach computer storage devices such as Disk Array Controllers and Tape Silos to servers. (In 2003) SANS are increasingly considered the best way of storing large volumes of data.

SANs originated to overcome the problems with network attached storage (NAS) devices, which like ordinary servers, are difficult to manage and expand, as well as adding to the Ethernet network traffic. NAS devices also suffer from the delays introduced by the operating systems' network stacks.

A SAN has a controller that makes hard disks in the SAN appear as a single entity (virtual hard disk). It also allows additional hard disks to be added to expand this virtual hard disk to enormous capacities, eliminating the problems of management and expansion experienced with other technologies. Because the hard disks are 'pooled', the utilisation of the storage capacity is usually also much higher.

SANs are typically linked to the network servers using optical fiber links, so isolating the traffic from the Ethernet used by the users' PCs.

At the time of writing (2003) the main problem with SANs is that systems from different manufacturers may not be compatible. Many systems have been pushed to the market before standards have been finalized.

See also