RAID

This article is about the data storage technology. For the police unit, see RAID (French Police unit). For other uses, see Raid (disambiguation).

RAID (/reɪd/; "redundant array of inexpensive disks"[1] or "redundant array of independent disks"[2]) is a data storage virtualization technology that combines multiple physical data storage components into one or more logical units for the purposes of data redundancy, performance improvement, or both. This is in contrast to the previous concept of highly reliable mainframe disk drives referred to as "single large expensive disk" (SLED).[3][1]

Data is distributed across the drives in one of several ways, referred to as RAID levels, depending on the required level of redundancy and performance. The different schemes, or data distribution layouts, are named by the word "RAID" followed by a number, for example RAID 0 or RAID 1. Each scheme, or RAID level, provides a different balance among the key goals: reliability, availability, performance, and capacity. RAID levels greater than RAID 0 provide protection against unrecoverable sector read errors, as well as against failures of whole physical drives.

  1. ^ a b Patterson, David; Gibson, Garth A.; Katz, Randy (1988). A Case for Redundant Arrays of Inexpensive Disks (RAID) (PDF). SIGMOD Conferences. Retrieved 2024-01-03.
  2. ^ Cite error: The named reference RAB was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference Katz was invoked but never defined (see the help page).