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Row diagonal parity is a scheme where one dedicated disk of parity is in a horizontal "row" like in RAID 4, but the other dedicated parity is calculated from blocks permuted ("diagonal") like in RAID 5 and 6. [1] Alternative terms for "row" and "diagonal" include "dedicated" and "distributed". [2]
Several methods, including dual check data computations (parity and Reed–Solomon), orthogonal dual parity check data and diagonal parity, have been used to implement RAID Level 6." [29] The second block is usually labeled Q, with the first block labeled P. Typically the P block is calculated as the parity (XORing) of the data, the same as RAID 5.
RAID 01, also called RAID 0+1, is a RAID level using a mirror of stripes, achieving both replication and sharing of data between disks. [3] The usable capacity of a RAID 01 array is the same as in a RAID 1 array made of the same drives, in which one half of the drives is used to mirror the other half.
RAID (/ r eɪ d /; redundant array of inexpensive disks or redundant array of independent disks) [1] [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.
In the case of a RAID 3 array of 12 drives, 11 drives participate in the XOR calculation shown above and yield a value that is then stored on the dedicated parity drive. Extensions and variations on the parity bit mechanism "double," "dual," or "diagonal" parity, are used in RAID-DP.
RAID stands for redundant array of independent disks (or, formerly, redundant array of inexpensive disks). RAID levels may refer to: Standard RAID levels, all the RAID configurations defined in the Common RAID Disk Drive Format standard, which is maintained by the Storage Networking Industry Association
In some RAID configurations, such as RAID 0, failure of a single member drive of the RAID array causes all stored data to be lost. In other RAID configurations, such as a RAID 5 that contains distributed parity and provides redundancy , if one member drive fails the data can be restored using the other drives in the array.
Those RAID systems made their way to the consumer market, for users wanting the fault-tolerance of RAID without investing in expensive SCSI drives. Fast consumer drives make it possible to build RAID systems at lower cost than with SCSI, but most ATA RAID controllers lack a dedicated buffer or high-performance XOR hardware for parity calculation.