When Is NAS Appropriate?

Rather than store data on local direct-attached storage (DAS), network attached storage (NAS) devices and storage area networks (SANs) provide two different approaches to consolidating data onto storage devices with massive amounts of disk space and fault-tolerant, high-availability features, such as RAID, clustering, and file or volume replication.

NAS devices, which are dedicated file servers accessible over one or more network file system protocols, such as Server Message Block (SMB) or Network File System (NFS), can be used for more than just storage of user home directories and shared files. Most Windows, Unix, and Linux server applications can read and write data files over a network path to a network share rather than to a local disk drive, and with a dedicated, high-speed network, the performance can be comparable to using local DAS.

SANs expose storage array volumes to servers or backup devices over a Fibre Channel or iSCSI networks, but do not manage the file systems written to them or provide file-level security; those duties must be performed by the OS of the connecting device. To the connecting server, a SAN volume acts like a partition on a local hard drive.