SAN architecture and topology
Storage Area Network architecture operates in a way that constructs all storage devices available to all servers on a Local Area Network (LAN) or Wide Area Network (WAN). As more storage devices are added to a SAN, they too will be accessible from any server in the larger network. The server acts only as a pathway between the end user and the stored data thus allowing network administrators to independently scale the storage or server processing power as requirements demand.
A SAN also allows numerous servers to access the same data so that repetition of information can be reduced, and allows data backup to occur directly over storage channels, reducing the bottleneck of the relatively slow LAN. Data is also more reliably available, as the breakdown of a single server will not cut off any storage from remaining servers.
STORAGE AREA NETWORK TOPOLOGY
ANOTHER STORAGE AREA NETWORK TOPOLOGY
All networked servers share storage devices as peer resources, which means that they are not the restricted property of any one server. SAN can be used to connect servers to storage, servers to each other, and storage to storage through hubs, switches and routers. A SAN carries only Input/Output (I/O) traffic between servers and storage devices and no general-purpose traffic such as electronic mail or other end-user applications are carried. This will prevent from any congestion in using a single network for all applications.
SAN use a various mixture of technologies, which include IBM's Enterprise Systems Connection (ESCON), Fiber Distributed Data Interface (FDDI), Asynchronous Transfer Mode (ATM), IBM's Serial Storage Architecture (SSA), and Fibre Channel. SAN architectures also let particular users or administrators to use a number of basic protocols such as TCP/IP and variations of SCSI. The popular implementation of SAN for open system is based on SCSI over Fibre Channel.
Storage Area Networks support disk mirroring, backup and restore, archival and retrieval of archived data, data migration from a storage device to another, and the sharing of data among different servers in a network.