RAID 5

Learn how data is written to a RAID 5 array.

RAID 5 stripes data across all disks in the array. RAID level 5 also writes array parity data. The parity data is spread across all the disks. For a RAID 5 array of three disks, array data and parity information are written in the following pattern:

Figure 1. RAID 5

If a disk fails in a RAID 5 array, you can continue to use the array normally. A RAID 5 array operating with a single Failed disk 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 disk by using data and parity blocks on the operational disks. If a second disk fails, the array will be placed in the Failed state and will not be accessible.