NFS

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Network File System (NFS) is a protocol originally developed by Sun Microsystems in 1984 and defined in RFCs 1094, 1813, and 3530 (obsoletes 3010), as a distributed file system which allows a computer to access files over a network as easily as if they were on its local disks. NFS is one of many protocols built on the Open Network Computing Remote Procedure Call system (ONC RPC).

The term "network file system" is also often used as a generic term.

Versions and variations

Version 2 of the protocol originally operated entirely over UDP and was meant to keep the protocol stateless, with locking (for example) implemented outside of the core protocol.

Version 3 introduced support for using TCP as transport. While it is true several vendors had already extended NFS Version 2 to support TCP as transport, Sun Microsystems introduced TCP as a transport for NFS at the same time it introduced Version 3. Using TCP as transport made using NFS over a WAN more feasible.

Version 4, influenced by AFS, and CIFS includes performance improvements, mandates strong security, and introduces a stateful protocol. Version 4 was the first version developed with the Internet Engineering Task Force (IETF) after Sun Microsystems handed over the development of the NFS protocols.

Various side-band protocols have been added to NFS, including:

  • The byte-range advisory Network Lock Manager (NLM) protocol which was added to support System V UNIX file locking APIs.
  • The remote quota reporting (RQUOTAD) protocol to allow NFS users to view their data storage quotas on NFS servers.

WebNFS is an extension to Version 2 and Version 3 which allows NFS to be more easily integrated into Web browsers and to enable operation through firewalls.

Platforms

NFS is strongly associated with UNIX systems, though it can be used on any platform such as Macintosh, Windows and Novell NetWare operating systems. The Server Message Block (SMB also known as CIFS) and NetWare Core Protocol (NCP), similar protocols, are equivalent implementations of a network file system under other operating systems. Cross-platform compatibility makes NFS and ideal network file system implementation.

See Also

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