Friday, February 22, 2008

Redundant Array of Individual Disks (RAID)

Types of RAID


RAID 0 or Disk Striping


Number of Minimum Disks Required=2


RAID 0 provides the highest performance but no redundancy. Data in the logical drive is striped (distributed) across several physical drives.

RAID 1 or Disk Mirroring


Number of Minimum Disks Required=2

Capacity=N/2

RAID 1 mirrors the data stored in one hard drive to another. RAID 1 can only be performed with two hard drives. If there are more than two hard drives, RAID (0+1) will be performed automatically.

RAID 3 or Disk Striping with Dedicated Parity Disk
Minimum Disk Required=3

Capacity=N-1

Redundancy=Yes

RAID 3 performs Block Striping with Dedicated Parity. One drive member is dedicated to storing the parity data. When a drive member fails, the controller can recover/ regenerate the lost data of the failed drive from the dedicated parity drive.

Raid 5 or Striping with Interspersed Parity
Minimum Disk Required=3

Capacity=N-1

Redundancy=Yes

RAID 5 is similar to RAID 3 but the parity data is not stored in one dedicated hard drive. Parity information is interspersed across the drive array. In the event of a failure, the controller can recover/regenerate the lost data of the failed drive from the other surviving drives.


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