File Servers

Updated on August 24, 2007

A file server provides a client with remote storage. A client's operating system and applications can read and write to a networked filesystem as though it were a local filesystem.

Network Operating Systems

Centralized data storage was one of the first applications of client-server networks. Hard drives were expensive in the 1980s, so it was cheaper for companies to network several PCs to a file server with a hard drive rather than buying a hard drive for each PC. Network operating systems (NOS) such as Novell's Netware and Banyan VINES were introduced during the 80's to fill this need and Apple and Sun added services (AppleShare, NFS and NIS) to their existing operating systems.

During the 90's, general purpose operating systems such as Linux and Windows NT took over file server functions from the specialized NOS's. Even consumer operating systems such as Windows and MacOS could do limited file serving. Specialized file servers didn't disappear though. Companies such as Auspex and Network Appliance developed network-attached storage (NAS) servers which contained RAIDs and ran special purpose operating systems, but still adhered to the by-then standard NFS and SMB network protocols.

SANs

Despite the similarity in names, storage area networks (SANs) are not the same as network-attached storage. SANs are groups of storage peripherals such as hard drives and tape drives that can be accessed directly by computers using a fast, low level protocol such as SCSI rather than a higher level network protocol like NFS. Therefore a SAN is more like a computer bus than a network. SANs are typically accessed by servers rather than by clients. Clients can then access those SAN-connected servers over a network just like any other server. SANs are used by organizations that maintain many servers. It's easier to backup and upgrade a single SAN rather than many individual servers.

WebDAV

A web server can also act as a file server, thanks to WebDAV. WebDAV stands for Web-based Distributed Authoring and Versioning and was designed to allow web browsers to edit documents on web servers, but since client operating systems such Windows and MacOS can access WebDAV enabled servers, this allows WebDAV servers to act as general file servers. However, WebDAV servers generally don't have the rigorous access control of typical file servers.

Further resources on file servers

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