What is a SAN (Storage Area Network)?

SAN stands for storage area network. Not to be confused with network attached storage, a SAN is essentially a type of local area network (LAN) designed to handle large data transfers at high speeds. This network architecture connects remote data storage devices, such as disk arrays, optical jukeboxes, and tape libraries, to a server array. These storage devices will be visible as local attachments to the operating system. A SAN typically supports data storage, replication, and retrieval.

SAN technology is similar to network attached storage (NAS) because it is also a type of local network storage. However, NAS uses file level protocols such as NFS (Network File System) or SMB/CIFS (Server Message Block/Common Internet File System) to transfer pieces of an abstract file rather than disk blocks. SANs, in contrast, traditionally use low-level network protocols or TCP/IP (Transmission Control Protocol/Internet Protocol) to allow easy integration into home computer networks.

SAN can sometimes refer to system area networks, which are high-performance computing clusters used for distributed processing applications that require a fast network connection. Storage area networks are designed only for data management.

Infrastructure
A FiberChannel (high speed cable) topology is the typical infrastructure used to handle a SAN’s storage communications. It has faster, more reliable access than the higher-level protocols. All major vendors currently offer some kind of Fiber Channel routing for SAN equipment. Fiber Channel routing solutions provide significant scalability benefits to the SAN architecture.

Benefits
SANs increase storage capacity by using multiple servers to consolidate private storage space into disk arrays. SANs are frequently used to manage transactional data that require fast, block-level access to hard drives. Such hard drives might include databases, email servers, or high-usage file servers.

The shared storage that a SAN provides simplifies administration and makes data mobility more flexible because cables and devices don’t need to be moved in order to transfer storage between servers. A SAN supports remote storage spread across distant locations.

More effective disaster recovery is another benefit of SANs. Servers can boot from the SAN itself, which enables fast and easy replacement of faulty servers. This quick replacement is possible because replacement servers on the SAN can be reconfigured to use the LUN (Logical Unit Number) of the faulty server. The replacement can take as little as half an hour! There are products that can speed up this process even further.

Click here for a podcast that explains how to build a SAN.

SAN stands for storage area network.