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EVENODD: An Efficient Scheme for Tolerating Double Disk Failures in RAID Architectures

Blaum, Mario and Brady, Jim and Bruck, Jehoshua and Menon, Jai (1995) EVENODD: An Efficient Scheme for Tolerating Double Disk Failures in RAID Architectures. IEEE Transactions on Computers, 44 (2). pp. 192-202. ISSN 0018-9340. doi:10.1109/12.364531.

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We present a novel method, that we call EVENODD, for tolerating up to two disk failures in RAID architectures. EVENODD employs the addition of only two redundant disks and consists of simple exclusive-OR computations. This redundant storage is optimal, in the sense that two failed disks cannot be retrieved with less than two redundant disks. A major advantage of EVENODD is that it only requires parity hardware, which is typically present in standard RAID-5 controllers. Hence, EVENODD can be implemented on standard RAID-5 controllers without any hardware changes. The most commonly used scheme that employes optimal redundant storage (i.e., two extra disks) is based on Reed-Solomon (RS) error-correcting codes. This scheme requires computation over finite fields and results in a more complex implementation. For example, we show that the complexity of implementing EVENODD in a disk array with 15 disks is about 50% of the one required when using the RS scheme. The new scheme is not limited to RAID architectures: it can be used in any system requiring large symbols and relatively short codes, for instance, in multitrack magnetic recording. To this end, we also present a decoding algorithm for one column (track) in error.

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Bruck, Jehoshua0000-0001-8474-0812
Additional Information:© 1994 IEEE. Manuscript received November 29, 1993; revised April II, 1994. Date of Current Version: 06 August 2002. This paper was presented in part at the International Symposium in Computer Architecture (ISCA), Chicago, IL, April 1994. We are grateful to the reviewers for their useful comments that helped in improving the presentation.
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INSPEC Accession Number4899533
Issue or Number:2
Record Number:CaltechAUTHORS:20120216-065736330
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Official Citation:Blaum, M.; Brady, J.; Bruck, J.; Jai Menon; , "EVENODD: an efficient scheme for tolerating double disk failures in RAID architectures," Computers, IEEE Transactions on , vol.44, no.2, pp.192-202, Feb 1995 doi: 10.1109/12.364531 URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:29320
Deposited By: Ruth Sustaita
Deposited On:16 Feb 2012 15:36
Last Modified:09 Nov 2021 17:06

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