RAID (p.5)

RAID Level 3

Level 3 represents a more sophisticated approach. Data can be recovered in the event of the failure of any disk, but the overall efficiency of disk use is better than in simple mirroring (Level 1).

In level 1 RAID (mirroring), data capacity is N/2, where N is the total number of disks. Don't be misled by the diagram above; parity bits for HDDs 1 and 2 would not actually fill up HDD 3. Since parity bits take up very little storage, with level 3 RAID, data capacity is N-1. The more disks in the array, the better the efficiency.

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