RAID 6

Learn how data is written to a RAID 6 array.

RAID 6 stripes data across all disks in the array. RAID level 6 also writes array "P" and "Q" parity data. The P and Q parity data, is spread across all the disks. For a RAID 6 array of four disks, array data and parity information are written in the following pattern:

Figure 1. RAID 6

If one or two disks fail in a RAID 6 array, you can continue to use the array normally. A RAID 6 array operating with a one or two Failed disks is said to be operating in Degraded mode. Whenever data is read from a Degraded disk array, the array controller recalculates the data on the failed disks by using data and parity blocks on the operational disks. A RAID 6 array with a single failed disk has similar protection to that of a RAID 5 array with no disk failures. If a third disk fails, the array will be placed in the Failed state and will not be accessible.