RAID 6 concepts

 

RAID 6 protection protects data from being lost because of a disk unit failure or because of damage to a disk. RAID 6 protection protects up to two disk unit failures.

 

RAID 6

If more than two disk units fail, restore the data from the backup media. Logically, the capacity of two disk units is dedicated to storing parity data in a parity set. However, in practice the parity data is spread among multiple disk units.

The minimum number of disk units in a parity set is 4. The maximum number of disk units in a parity set is 18.

When a RAID 6 parity set is started, all of the disk units contain parity. Restoring data to a disk pool that has disk units with device parity protection may take longer than a disk pool that contains only unprotected disk units.

IBM recommends that you use more than four disk units in a RAID 6 parity set, because the capacity of two disk units is dedicated to storing parity data in a parity set.

• How RAID 6 protection works
  This topic describes how RAID 6 protection works.

• Elements of RAID 6 protection
  This topic describes and illustrates RAID 6 protection.

• How RAID 6 affects performance
  This topic describes the performance of using RAID 6 protection.

• Benefits of RAID 6 protection
  There are many benefits of using RAID 6 parity protection.

• Costs and limitations of RAID 6 protection
  There are costs and limitations when using RAID 6 protection.

• Parity set optimization for RAID 6 protection
  RAID 6 IOAs provide optimal performance, capacity, and balance, so selecting any of the parity set optimizations will not affect the outcome of the parity sets performance.

• Read operations on a failed disk unit
  To access the data that was contained on a failed disk unit, device parity protection must read each disk unit in the parity set that contains the failed disk unit.

• IOA migration
  There are considerations and limitations when migrating an IOA.

 

Parent topic:

Device parity protection concepts