System Administration Guide
Chapter 8, Administering virtual disks

RAID

RAID

RAID is an acronym for redundant array of inexpensive disks.

RAIDs are replacing single, large, expensive disks because of the need for large, shared, high-performance, network-based storage systems. Such systems read and write data in parallel, and do so faster than a single disk system. They are also more reliable: the disks store data redundantly so that if one of them fails, the lost information can be interpolated from the other drives. Finally, they are cheaper. High capacity drives typically cost more per unit of storage than older, lower capacity drives, and disk arrays can use the cheaper units to achieve performance equal or superior to the more expensive, larger drives.