NAS: The Storage Workhorse.

As the LAN (Local Area Network) concept grew, networking products became more specialized and network communications tasks were offloaded from general-purpose servers to routers and switches.

Widespread growth in LANs began to highlight the mounting storage and I/O bottlenecks that awaited the networked computing world.

The typical LAN server often used between 30% and 60% of its processor cycles performing I/O activities. In contrast to general-purpose servers with large operating systems and applications software, NAS servers were designed to serve files and perform I/O much more efficiently by providing storage functions for many application servers.

The offloading of storage and I/O functions to the simplified and thinner NAS server frees CPU or server cycles by consolidating storage devices into smaller networks avoiding the overhead and complexity of general-purpose servers. NAS servers are typically less expensive than other servers. NAS servers execute optimized operating system software and file system data transfer protocols such as NFS, CIFS, NCP, and HTTP. The NAS server looks like an ordinary server to network applications and a large storage device to the client (see Fig). The NAS servers are directly accessible from all clients and other servers on the network, most commonly with Ethernet. NAS servers use services that support data at the file level as opposed to inefficient block level I/O, along with sharing certain files across multiple computing platforms. NAS is a form of SAN architecture and is available today and is best positioned for small to midsize data processing operations. The SAN market overlaps the high-end of the NAS market, b ut the SAN will typically serve larger installations. Look for NAS to soon contain an outboard tape automation component for backup, recovery, and HSM functions. Later, NAS and SAN will likely merge with the NAS server becoming a candidate for the brains of the SAN.