RAID Level 5¶
Block-Interleaved, Distributed Parity¶
- In this scheme, we make parity blocks. Parity block \(j\) stores the \(XOR\) of bits from block \(j\) of each disk.
Given 5 Disks
| D1 | D2 | D3 | D4 | D5 |
|---|---|---|---|---|
| P0 | 0 | 1 | 2 | 3 |
| 4 | P1 | 5 | 6 | 7 |
| 8 | 9 | P2 | 10 | 11 |
| 12 | 13 | 14 | P3 | 15 |
| 16 | 17 | 18 | 19 | P4 |
Since block writes occur in parallel, the writing isn't slowed down. The \(n^{th}\) parity block stores the information about the \(n^{th}\) row in this table. If one disk is corrupted, we can restore its information from the parity block.