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 is written in the following pattern:

If one or two disks fail in a RAID 6 array, you can continue to use the array normally. A RAID 6 array that is 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 is placed in the failed state and is not be accessible.