Dell PowerEdge R830 Integrated Remote Access Controller 8 Version 2.70.70.70 U - Page 183

RAID level 6 - striping with additional distributed parity, Managing storage devices

Page 183 highlights

RAID 5 characteristics: • Groups n disks as one large virtual disk with a capacity of (n-1) disks. • Redundant information (parity) is alternately stored on all disks. • When a disk fails, the virtual disk still works, but it is operating in a degraded state. The data is reconstructed from the surviving disks. • Better read performance, but slower write performance. • Redundancy for protection of data. RAID level 6 - striping with additional distributed parity RAID 6 provides data redundancy by using data striping in combination with parity information. Similar to RAID 5, the parity is distributed within each stripe. RAID 6, however, uses an additional physical disk to maintain parity, such that each stripe in the disk group maintains two disk blocks with parity information. The additional parity provides data protection in the event of two disk failures. In the following image, the two sets of parity information are identified as P and Q. RAID 6 characteristics: • Groups n disks as one large virtual disk with a capacity of (n-2) disks. • Redundant information (parity) is alternately stored on all disks. • The virtual disk remains functional with up to two disk failures. The data is reconstructed from the surviving disks. Managing storage devices 183

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RAID 5 characteristics:
Groups
n
disks as one large virtual disk with a capacity of (
n
-1) disks.
Redundant information (parity) is alternately stored on all disks.
When a disk fails, the virtual disk still works, but it is operating in a degraded state. The data is reconstructed from the surviving disks.
Better read performance, but slower write performance.
Redundancy for protection of data.
RAID level 6 - striping with additional distributed parity
RAID 6 provides data redundancy by using data striping in combination with parity information. Similar to RAID 5, the parity is distributed
within each stripe. RAID 6, however, uses an additional physical disk to maintain parity, such that each stripe in the disk group maintains
two disk blocks with parity information. The additional parity provides data protection in the event of two disk failures. In the following
image, the two sets of parity information are identified as
P
and
Q
.
RAID 6 characteristics:
Groups
n
disks as one large virtual disk with a capacity of (
n
-2) disks.
Redundant information (parity) is alternately stored on all disks.
The virtual disk remains functional with up to two disk failures. The data is reconstructed from the surviving disks.
Managing storage devices
183