Redundant Array of Inexpensive Nodes 5279469 199371516 2008-03-19T16:30:27Z Pol098 169132 wording In [[computer storage]] the primary mechanism for providing reliable storage of data is the Redundant Array of Inexpensive/Independent Disks ([[RAID]]). Redundant RAID configurations use multiple physical [[hard disk]]s in [[wikt:concert|concert]] to limit the chances that a [[hardware]] failure will result in a loss of data. For example, the same data is written to both discs in a [[redundant array of independent disks#RAID 1|RAID 1 mirror configuration]], so that there is no loss of data should any one disk fail. A newer, more advanced, way of protecting [[computer storage]] is through a '''Redundant Array of Inexpensive Nodes or RAIN'''. While RAID relies on specialized [[Disk controller|drive controllers]] or [[operating system]] [[device driver]]s, RAIN relies on [[Computer software|software]] to organize multiple separate [[Server (computing)|computer servers]] to provide data reliability. Instead of storing multiple copies of the same data on physically separate [[hard disk]]s on a server, data is [[Replication (computer science)|replicated]] to multiple servers. The [[Computer software|software]] that manages the [[Computer cluster|cluster]] of RAIN servers knows where each copy is and, in the event of a server failure, can make additional copies as necessary to keep an appropriate level of [[wikt:redundancy|redundancy]]. RAIN can also be used with tasks which require many [[instructions per second]] to be processed. Instead of using a "tightly-coupled" [[Computer cluster|computing cluster]] with specialized [[hardware]], collections of inexpensive RAIN nodes can be assembled. The management [[Computer software|software]] transmits tasks to various computers and, in the event of a failure, will retry the task until a node responds. Many of the [[distributed computing]] projects around the globe utilize, to some degree, a RAIN strategy. Many of the distributed [[file sharing]] services such as [[Gnutella]] and [[eDonkey network|eDonkey]] are somewhat similar to RAIN systems, but they do not provide adequate redundancy by design—if none of the sharing users online have a copy of some part of a file, the file becomes inaccessible. A [[distributed hash table]] is a better basis for implementing such a service, and the few large-scale [[distributed file system]]s that exist are based on them (for example, the [[chord project|chord]] and [[Coral Content Distribution Network|coral]] projects). ==External links== * [http://www.networkworld.com/details/6769.html?def RAIN definition from NetworkWorld.com] * [http://www.hoise.com/CEC/AE-PR-04-97-2.html RAIN in Neurocomputing] {{compu-storage-stub}} [[Category:RAID]]