Quote (Jason89 @ 12 Jul 2012 19:11)
RAID
From Wikipedia, the free encyclopedia
This article is about the data storage technology. For other uses, see Raid (disambiguation).
RAID (redundant array of independent disks, originally redundant array of inexpensive disks[1][2]) is a storage technology that combines multiple disk drive components into a logical unit. Data is distributed across the drives in one of several ways called "RAID levels", depending on what level of redundancy and performance (via parallel communication) is required.
RAID is an example of storage virtualization and was first defined by David Patterson, Garth A. Gibson, and Randy Katz at the University of California, Berkeley in 1987.[3] Marketers representing industry RAID manufacturers later attempted to reinvent the term to describe a redundant array of independent disks as a means of dissociating a low-cost expectation from RAID technology.[4]
RAID is now used as an umbrella term for computer data storage schemes that can divide and replicate data among multiple physical drives. The physical drives are said to be in a RAID array,[5] which is accessed by the operating system as one single drive. The different schemes or architectures are named by the word RAID followed by a number (e.g., RAID 0, RAID 1). Each scheme provides a different balance between three key goals: resiliency, performance, and capacity.
Contents [hide]
1 Standard levels
2 Nested (hybrid) RAID
3 RAID parity
4 RAID 6 replacing RAID 5 in enterprise environments
5 RAID 10 versus RAID 5 in relational databases
6 New RAID classification
7 Non-standard levels
8 Data backup
9 Implementations
9.1 Software-based RAID
9.1.1 Volume manager support
9.1.2 File system support
9.1.3 Other support
9.2 Hardware-based RAID
9.3 Firmware/driver-based RAID
9.4 Hot spares
9.5 Data scrubbing / Patrol read
10 Reliability terms
11 Problems with RAID
11.1 Correlated failures
11.2 Atomicity
11.3 Write cache reliability
11.4 Equipment compatibility
11.5 Data recovery in the event of a failed array
11.6 Drive error recovery algorithms
11.7 Recovery time is increasing
11.8 Operator skills, correct operation
11.8.1 Hardware labeling issues
11.9 Other problems
12 History
13 Non-RAID drive architectures
14 Also See
15 References
16 External links
[edit]Standard levels