- Redundant Array of Inexpensive Nodes
Redundant/Reliable Array of Inexpensive/Independent Nodes (RAIN) is an
open architecture approach tocomputer storage , that combines commodity or low-cost computinghardware with highly intelligent management software to surpass the reliability and availability qualities of the expensive high end storage systems.RAIN is a newer, more advanced, way of protecting
computer storage thanRAID ("Redundant Array of Inexpensive/Independent Disks") approach, which uses multiple physicalhard disk s in 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 RAID 1 mirror configuration, so that there is no loss of data should any one disk fail. While RAID relies on specialized drive controllers oroperating system device driver s, RAIN relies on software to organize multiple separate computer servers to provide data reliability. Instead of storing multiple copies of the same data on physically separatehard disk s on a server, data is replicated to multiple servers. The software that manages the 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 .RAIN can also be used with tasks which require many
instructions per second to be processed. Instead of using a "tightly-coupled" computing cluster with specializedhardware , collections of inexpensive RAIN nodes can be assembled. The management software transmits tasks to various computers and, in the event of a failure, will retry the task until a node responds. Many of thedistributed computing projects around the globe utilize, to some degree, a RAIN strategy.Many of the distributed
file sharing services such asGnutella and 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. Adistributed hash table is a better basis for implementing such a service, and the few large-scaledistributed file system s that exist are based on them (for example, the chord and coral projects).Further reading
* cite paper | last= Bohossian | first= Vasken | author= | authorlink= | coauthors= Charles C. Fan, Paul S. LeMahieu, Marc D. Riedel, Lihao Xu, Jehoshua Bruck | title= Computing in the RAIN. A Reliable Array of Independent Nodes | version= | pages=
publisher= | date= September 1999 | doi= | url= http://www.paradise.caltech.edu/papers/etr029.pdf | format= pdf | id= | accessdate= July 2008External 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]
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