Nested RAIDs

The architecture of RAID levels 10, 50, 60, and 70 represents RAID 0 which components are RAID 1, 5, 6 and 7 respectively instead of separate drives. These levels can be described as grouped or nested RAID levels. The nested level group size parameter defines how many drives are used in each of RAID 5, 6 or 7 components. RAID 10 always use group size equal to 2. the drive number in a nested RAID shall be a multiple of the group size.

RAID 10 – striped set from a series of mirrored drives that is RAID 0, which components are RAIDs 1 instead of separate drives. Each RAID 1 mirror of RAID 10 always consists of two drives, the minimum number of RAIDs 1 in a stripe array is 2. Thus, in RAID 10 the minimum number of drives is 4. Data integrity is maintained in case of failure of half drives; the irreversible RAID destruction occurs when two drives of one mirrored pair already fail.

RAID 50 – RAID 0 striping combination across multiple RAIDs level 5. With such a combination, RAID 50 may show better performance with reduced latency. The group size is at least 3 drives. Recoverable from 1 drive failure in each group.

RAID 60 – RAID 0 striping combination across multiple RAIDs level 6. RAID 60 is the equivalent of RAID 50 with a higher level of fault tolerance. The group size is at least 4 drives. Recoverable from 2 failures in each group.

RAID 70 – RAID 0 striping combination across multiple RAIDs level 7. RAID 70 is the equivalent of RAID 60 with a higher level of fault tolerance. The group size is at least 4 drives. Recoverable from 3 failures in each group.