Editing RAID (section)

== History ==
The term "RAID" was invented by [[David Patterson (computer scientist)|David Patterson]], [[Garth Gibson]], and [[Randy Katz]] at the [[University of California, Berkeley]] in 1987. In their June 1988 paper "A Case for Redundant Arrays of Inexpensive Disks (RAID)", presented at the [[SIGMOD]] Conference, they argued that the top-performing [[mainframe computer|mainframe]] disk drives of the time could be beaten on performance by an array of the inexpensive drives that had been developed for the growing [[personal computer]] market. Although failures would rise in proportion to the number of drives, by configuring for redundancy, the reliability of an array could far exceed that of any large single drive.<ref>{{cite magazine |url=http://www.computerworld.com/article/2573180/data-center/the-story-so-far.html |title=The Story So Far |first=Frank |last=Hayes |magazine=Computerworld |date=November 17, 2003 |access-date=November 18, 2016 |quote=Patterson recalled the beginnings of his RAID project in 1987. [...] 1988: David A. Patterson leads a team that defines RAID standards for improved performance, reliability and scalability.}}</ref>

Although not yet using that terminology, the technologies of the five levels of RAID named in the June 1988 paper were used in various products prior to the paper's publication,<ref name="Katz">{{cite web
 | url = http://web.eecs.umich.edu/~michjc/eecs584/Papers/katz-2010.pdf
 | title = RAID: A Personal Recollection of How Storage Became a System
 | date = October 2010 | access-date = 2015-01-18
 | first = Randy H. |last = Katz | publisher = IEEE Computer Society
 | website = eecs.umich.edu | quote = We were not the first to think of the idea of replacing what Patterson described as a slow large expensive disk (SLED) with an array of inexpensive disks. For example, the concept of disk mirroring, pioneered by Tandem, was well known, and some storage products had already been constructed around arrays of small disks.
}}</ref> including the following:

* Mirroring (RAID 1) was well established in the 1970s including, for example, [[Tandem Computers|Tandem]] [[NonStop (server computers)|NonStop Systems]].
* In 1977, Norman Ken Ouchi at [[IBM]] filed a patent disclosing what was subsequently named RAID&nbsp;4.<ref>{{US patent reference |number=4092732 |y=1978 |m=05 |d=30 |inventor=Norman Ken Ouchi |title=System for Recovering Data Stored in Failed Memory Unit}}</ref>
* Around 1983, [[Digital Equipment Corporation|DEC]] began shipping subsystem mirrored RA8X disk drives (now known as RAID&nbsp;1) as part of its HSC50 subsystem.<ref>{{cite web |url = http://www.textfiles.com/bitsavers/pdf/dec/ci/EK-HS571-TM-001_HSC_hwTech.pdf |title = HSC50/70 Hardware Technical Manual |pages = 29, 32 |date = July 1986 |access-date = 2014-01-03 |publisher = [[Digital Equipment Corporation|DEC]] |archive-date = 2016-03-04 |archive-url = https://web.archive.org/web/20160304032213/http://www.textfiles.com/bitsavers/pdf/dec/ci/EK-HS571-TM-001_HSC_hwTech.pdf |url-status = dead }}</ref>
* In 1986, Clark et al. at IBM filed a patent disclosing what was subsequently named RAID&nbsp;5.<ref>{{US patent reference |number=4761785 |y=1988 |m=08 |d=02 |inventor=Brian E. Clark, et al. |title=Parity Spreading to Enhance Storage Access}}</ref>
* Around 1988, the [[Thinking Machines Corporation|Thinking Machines']] [[DataVault]] used error correction codes (now known as RAID&nbsp;2) in an array of disk drives.<ref>{{US patent reference |number=4899342 |y=1990 |m=02 |d=06 |inventor=David Potter et al. |title=Method and Apparatus for Operating Multi-Unit Array of Memories}} See also [http://www.svisions.com/sv/raid-patent.html The Connection Machine (1988)]</ref> A similar approach was used in the early 1960s on the [[IBM&nbsp;353]].<ref>{{cite web
 | url = http://bitsavers.trailing-edge.com/pdf/ibm/7030/22-6530-2_7030RefMan.pdf#page=160
 | title = IBM 7030 Data Processing System: Reference Manual
 | year = 1960 | access-date = 2015-01-17
 | publisher = [[IBM]] | website = bitsavers.trailing-edge.com
 | format = PDF | page = 157
 | quote = Since a large number of bits are handled in parallel, it is practical to use error checking and correction (ECC) bits, and each 39 bit byte is composed of 32 data bits and seven ECC bits. The ECC bits accompany all data transferred to or from the high-speed disks, and, on reading, are used to correct a single bit error in a byte and detect double and most multiple errors in a byte.
}}</ref><ref>{{cite web |date=2009-06-18 |title=IBM Stretch (aka IBM 7030 Data Processing System) |url=http://www.brouhaha.com/~eric/retrocomputing/ibm/stretch/ |access-date=2015-01-17 |website=brouhaha.com |quote=A typical IBM&nbsp;7030 Data Processing System might have been {{sic|comprised|hide=y| of}} the following units: [...] IBM&nbsp;353 Disk Storage Unit{{snd}} similar to IBM&nbsp;1301 Disk File, but much faster. 2,097,152 (2^21) 72-bit words (64 data bits and 8 ECC bits), 125,000 words per second}}</ref>

Industry manufacturers later redefined the RAID acronym to stand for "redundant array of ''independent'' disks".<ref name="RAB">"Originally referred to as Redundant Array of Inexpensive Disks, the term RAID was first published in the late 1980s by Patterson, Gibson, and Katz of the University of California at Berkeley. (The RAID Advisory Board has since substituted the term Inexpensive with Independent.)" Storage Area Network Fundamentals; Meeta Gupta; Cisco Press; {{ISBN|978-1-58705-065-7}}; Appendix A.</ref><ref name="Patterson_1994">{{Cite journal |first1=Peter |last1=Chen |first2=Edward |last2=Lee |first3=Garth |last3=Gibson |first4=Randy |last4=Katz |first5=David |last5=Patterson |title=RAID: High-Performance, Reliable Secondary Storage |journal=ACM Computing Surveys |volume=26 |issue=2 |pages=145–185 |year=1994 |doi=10.1145/176979.176981 |citeseerx=10.1.1.41.3889 |s2cid=207178693}}</ref><ref>{{Cite book |last1=Donald |first1=L. |title=MCSA/MCSE 2006 JumpStart Computer and Network Basics |publisher=SYBEX |location=Glasgow |edition=2nd |year=2003}}</ref><ref>{{Cite web |url=http://foldoc.org/RAID |title=Redundant Arrays of Independent Disk |work=Free On-line Dictionary of Computing (FOLDOC) |publisher=Imperial College Department of Computing |editor-last=Howe |editor-first=Denis |access-date=2011-11-10}}</ref>