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Appendix B – Introduction to RAID levels
RAID 50
RAID 50 arrays are formed by striping data across RAID 5 sub-arrays. They offer better
performance than RAID 5 alone, particularly in write speed, but do not have the speed of a pure
RAID 0 array. Storage efficiency and fault tolerance vary depending on the number and size of
sub-arrays compared to the array as a whole. RAID 50 resembles RAID 30 in its characteristics.
RAID 50 is better suited for use with smaller files.
RAID 50: Block striping with interspersed parity combined with block striping
Characteristics:
Capacity: (Size of smallest drive) × (No. of drives
in each subarray - 1) × (No. of subarrays).
Requires a minimum of six drives. Number of
drives must be divisible by two numbers: 2 or
higher (no. of subarrays) and 3 or higher (disks
within each RAID 3 subarray)
Excellent fault tolerance, increasing with the
number of RAID 5 subarrays (and hence the
number of parity disks)
Arrangement of data blocks saved on a six-drive Level 50 array
Recommended use:
Critical
databases
requiring
speed,
resilience and high
capacity.
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