Network Attached Storage (NAS)

A NAS unit is essentially a self-contained computer connected to a network with the sole purpose of supplying file-based data storage services to other devices on the network. The operating system and other software on the NAS unit provide the functionality of data storage, access control, and the management of these functions. NAS systems are not designed to carry out general-purpose computing tasks, although it may be possible to run other embedded software such as a backup agent of anti-virus product. Typically, NAS units do not require keyboard or display acccess. Instead, they are controlled and configured over the network through an installable application or web-based GUI.

NAS systems contain one or more hard disks, often arranged into logical, redundant storage containers or RAID arrays (redundant arrays of inexpensive/independent disks). NAS removes the responsibility of file serving from other servers on the network and can provide significant cost savings in server OS licensing.

Availability of data might potentially be increased with NAS if it provides built-in RAID and clustering. Performance can be increased by NAS because the file serving process is the sold function of the NAS system whereas server systems are typically responsible for processing/applications. The performance of NAS devices depends heavily on the bandwidth of your network (speed, current traffic) and on the amount of cache memory (RAM) on the NAS device(s).

It should be noted that NAS is effectively a server in itself, with all major components of a typical PC – a CPU, motherboard, RAM, etc. – and its reliability is a function of how well it is designed internally. A NAS without redundant data access paths, redundant controllers, redundant power supplies, is less reliable than Direct Attached Storage (DAS) connected to a server which does have redundancy for its major components.

NAS is useful for more than just general centralized storage provided to client computers in environments with large amounts of data. NAS can enable simpler and lower cost systems such as small business email and web server systems by providing storage services. NAS is an intuitive fit for any environment with a large amount of multi-media data. The price of NAS appliances has plummeted in recent years, offering flexible network-based storage to the home consumer market for little more than the cost of a regular USB or FireWire external hard disk.

When architected properly, NAS can be an effective solution for data backup and archive serving as a disk target for backup/archive applications.