Knowing NAS from SAN

Network-attached storage (NAS) is not just storage-area network (SAN) spelled

backwards. Though they are often confused and may be used in tandem, they

are very different technologies.

NAS devices are attached directly to a network and act as dedicated,

high- performance storage resources.

A SAN is a high-speed, special-purpose network or subnetwork that connects

different kinds of storage devices. SANs are separate from agency local-area

networks or wide-area networks and are used exclusively for moving data

efficiently among servers and storage devices. A SAN is usually deployed

near mainframes, but may also extend to remote locations for backup and

archival storage, using WAN technology.

Although NAS and SAN are different technologies, they can work together.

A NAS can attach through a SAN to the storage system. In addition, some

IT administrators put NAS behind a server, instead of out on the network,

to create a SAN-like environment.

Still, neither is likely to replace the other because they are targeted

at different applications. Although a NAS is great for sharing general files

among a small workgroup, most organizations would not store financial documents

or other sensitive data on a NAS device. This type of data protection is

usually only offered via a SAN is a glasshouse environment. In addition,

only SANs are equipped with the reliability and scalability to handle the

"database pounding" associated with transactional, heavy applications.