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Appendix B – Introduction to RAID levels
RAID 30
RAID 30 arrays are formed by striping data across RAID 3 sub-arrays. They offer better
performance than RAID 3 alone 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 30 resembles RAID 50 in its characteristics. RAID 30 is better
suited for use with larger files.
RAID 30: Byte striping with 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 (drives
within each RAID 3 subarray)
Excellent fault tolerance, increasing with the
number of RAID 3 subarrays (and hence the
number of parity disks)
Arrangement of data blocks saved on a six-drive Level 30 array
Recommended use:
Critical multimedia /
file servers requiring
speed, resilience and
high capacity.
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