Appendix B – Introduction to RAID levels
71
RAID 3
RAID 3 uses a mathematical expression that compares data from two drives and calculates a
third piece of data called “parity”. Should one of the drives fail, parity data can be used to rebuild
the failed data. Under RAID 3, parity data is stored on a dedicated parity disk. If two or more
disks were to fail however, data would be lost. Data on RAID 3 is byte-interleaved. While the low
ratio of parity disks to data disks ensures high efficiency, the parity disk is accessed more than
the others and so is also more likely to fail.
RAID 3:
Parallel transfer with parity
Characteristics: Recommended
use:
The data block is subdivided, i.e. striped, and
written on the data disks. Stripe activity is
generated on Writes, recorded on the parity disk,
and checked on Reads.
Very high Read and Write data transfer rates.
Disk failure has a low impact on throughput.
Low ratio of ECC (Parity) disks to data disks
means high efficiency.
Requires a minimum of three drives.
Video production and
live streaming
Image editing
Video editing
Any application
requiring high
throughput
Arrangement of data blocks saved on a Level 3 array
