- Last Updated: 02 June 2010
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Main source: http://en.wikipedia.org/wiki/RAID
RAID = Redundant Array of Inexpensive Disks (old), Redundant Array of Independent Disks (new)
Goals: Improve data reliability / I/O throughput
Mirroring: copying data other disks
Striping: distributing data among disks
Parity: Redundant information for reliability and error correction
RAID 0 (at least 2 drives)
Striping: content is dispatched through the discs. No redundancy, highest I/O. Usage for scratch workspace which needs high speed and no reliability. One disk failure leads to unrecoverable data loss.
RAID 1 (at least 2 drives)
Mirroring: content is copied to all disks. There is only small or no I/O speed benefit, but a data redundancy and safety.
RAID 5 (at least 3 drives)
Parity information is distributed on the drives. If only one drive fails, the data is still safe. This RAID level also gives a higher performance and is one of the most used modes.