Redundant Array of Independent Disks

(RAID) A standard naming convention for various ways of using multiple disk drives to provide redundancy and distributed I/O.

The original ("..Inexpensive..") term referred to the 3.5 and 5.25 inch disks used for the first RAID system but no longer applies. As solid state drives are becoming a practical repacement for magnetic disks, "RAID" is sometimes expanded as "Redundant Array of Independent Drives".

The following standard RAID specifications exist:

 RAID 0	Non-redundant striped array
 RAID 1	Mirrored arrays
 RAID 2	Parallel array with ECC
 RAID 3	Parallel array with parity
 RAID 4	Striped array with parity
 RAID 5	Striped array with rotating parity

RAID originated in a project at the computer science department of the University of California at Berkeley, under the direction of Professor Katz, in conjunction with Professor John Ousterhout and Professor David Patterson. A prototype disk array file server with a capacity of 40 GBytes and a sustained bandwidth of 80 MBytes/second was interfaced to a 1 Gb/s local area network. It was planned to extend the storage array to include automated optical disks and magnetic tapes.

ftp://wuarchive.wustl.edu/doc/techreports/berkeley.edu/raid/raidPapers. http://HTTP.CS.Berkeley.EDU/projects/parallel/research_summaries/14-Computer-Architecture/.

["A Case for Redundant Arrays of Inexpensive Disks (RAID)", "D. A. Patterson and G. Gibson and R. H. Katz", Proc ACM SIGMOD Conf, Chicago, IL, Jun 1988].

["Introduction to Redundant Arrays of Inexpensive Disks (RAID)", "D. A. Patterson and P. Chen and G. Gibson and R. H. Katz", IEEE COMPCON 89, San Francisco, Feb-Mar 1989].