Example: Writing operations on a failed disk unit

 

An illustration shows how device parity protection works.

The following figure shows a failed disk unit under an IOA with RAID 5 device parity protection. This parity set has four disk units. Each section of the disk unit is marked with a number. Parity sectors are noted with a p. Disk unit 3 is failed. Disk unit 1 shows sectors 1, 2, 3, and 4p. Disk unit 2 shows sectors 4, 1, 2, and 3p. Failed disk unit 3 shows sectors 3, 4, 1, and 2p. Disk unit 4 shows sectors 2, 3, 4, and 1p.

Figure 1. Device parity set with failed disk unit.

RAID 6 operations are derived from RAID 5, but at a further level of complexity. Because the concept is similar to RAID 5, RAID 6 operations are not described.

 

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Device parity protection examples