System information

Appendix
A-4
A.4 RAID 3
In RAID 3, all data is divided into pieces, after which the system calculates the parity of these pieces. The pieces are
written to separate disks in parallel with the writing of the parity data. In the event of disk failure, the parity data can be
used to rebuild the lost data. If two or more disks fail, data will be lost. While the low ratio of parity disks to data disks
ensures high efficiency, the parity disk is accessed more frequently than other disks, therefore making it unsuitable for
random write access.
RAID 3: Parallel transfer with parity
Characteristics
• Storage capacity = (number of disks -1) x (capacity of the smallest disk)
• A minimum of three disks are required.
• Fault tolerance: Good
• The data block is striped, written on the data disks. Stripe activity is generated on writes, recorded on the
parity disk and checked on reads.
• Low ratio of (parity) disks to data disks ensures high efficiency.
Recommended use
• Video production and live streaming
• Image editing
• Video editing
• Any application requiring high throughput
A
A B PAB
Hot Spare
C D PCD
E F PEF
B
C
G
F
D
E
CONTROLLER
Figure A-3 RAID 3 disk array