The striping strategy is to spread the data across multiple disks at the bit level. The error correcting code has the property that data lost from failure of one data disk can be recovered by reading from one of the error correction disks. Benefits High reliability. Slightly better storage efficiency and cost advantage over mirroring. The error correction disks must all be updated whenever any data are written.
Write performance is less than the throughput of a single disk.
Drawbacks Since data are striped at the bit level, all reads and all writes require accessing multiple disks. This has the effect that performance is worse than for a single disk. RAID 2 is not commercially viable and can be safely forgotten. RAID 3 RAID level 3 combines the same fine-grained striping strategy as level 2, but uses only one additional disk for error correction instead of several. The error correction code is compute by taking the exclusive or of all the data disks.