TECH LIBRARY
RAID
RAID is technology of arranging of array of disks and usually seen by operating system as one single disk. It's an acronym to describe a Redundant Array of Independent Disks (originally it was defined as Redundant Array of Inexpensive Disks in 1987).
RAID is used to achieve higher level of reliability or speed (or both) using less reliable and slower speed disk drives. There are several different schemes of RAID configuration with different advantages and disadvantages.
RAID Level |
Alias |
Goal |
Description |
Disks (minimum) |
RAID 0 |
Striping |
Speed |
|
2 |
RAID 1 |
Mirroring |
Reliability |
|
2 |
RAID 2 |
Hamming code parity |
|
|
3 |
RAID 3 |
Striped set w/dedicated parity |
|
|
3 |
RAID 4 |
Block level parity |
|
|
3 |
RAID 5 |
Striped set w/distributed parity |
|
|
3 |
RAID 6 |
Striped set w/dual distributed parity |
|
|
4 |