Compaq Infortrend manual 7 RAID, 8 RAID, Raid

IMPORTANT!

•“RAID (0+1)” will not appear in the list of RAID levels supported by the controller. If you wish to perform RAID 1, the controller will determine whether to perform RAID 1 or RAID (0+1). This will depend on the number of drives that has been selected for the logical drive.

RAID 3

Disk Striping with Dedicated Parity Disk

Figure 1 - 7 RAID 3

Logical Drive		Ph y si c al D i s ks
			Dedicated
Block 1			Parity
	S t r i p i n g
Block 2
Block 3	Block 1	Block 2	Parity (1,2)
Block 4	Block 3	Block 4	Parity (3,4)
Block 5	Block 5	Block 6	Parity (5,6)
	Block 7	Block 8	Parity (7,8)
Block 6
	.	.	.
Block 7
	.	.	.

Block 8

.

.

RAID 3

Minimum	3
Disks required
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

Striping with Interspersed Parity

Figure 1 - 8 RAID 5

Logical Drive		Physical Disks
Block 1	Striping + non-dedicated Parity
Block 2
Block 3	Block 1	Block 2	Parity (1,2)
Block 4	Parity (3,4)	Block 3	Block 4
Block 5	Block 6	Parity (5,6)	Block 5
	Block 7	Block 8	Parity (7,8)
Block 6
	.	.	.
Block 7
	.	.	.

Block 8

.

.

RAID 5

Minimum	3
Disks required
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.

RAID 30 an RAID 50 are implemented as logical volumes, please refer to the proceeding discussions for more details.

Functional Description 1-5