Reference Work Entry

Encyclopedia of Database Systems

pp 2359-2359

Redundant Arrays of Independent Disks

  • Kenichi WadaAffiliated withHitachi Limited


Array; Disk array; Storage array; RAID


A set of disks from one or more commonly accessible disk subsystems is combined with a body of control software in which part of the physical storage capacity is used to store redundant information about user data stored on the remainder of the storage capacity. The redundant information enables regeneration of user data in a storage emergency in which a disk in the array or an access path fails.

Key Points

The term RAID was adopted from the 1988 SIGMOD paper “A Case for Redundant Arrays of Inexpensive Disks (RAID).” In the paper, RAID refers to a group of storage schemes that divide and replicate data among multiple disks to provide better performance, cost and power consumption rate with reasonable availability comparing with conventional Single Large Expensive Disk (SLED) used for Mainframe. Currently, the term of “independent” is usually used rather than “inexpensive” because SLED becomes obsolete.

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