RAID 10

Learn how data is written to a RAID 10 array.

RAID 10 uses mirrored pairs to redundantly store data. The array must contain an even number of disks. Two is the minimum number of disks needed to create a RAID 10 array. The data is striped across the mirrored pairs. For example, a RAID 10 array of four disks would have data written to it in the following pattern:

Figure 1. RAID 10

RAID 10 tolerates multiple disk failures. If one disk in each mirrored pair fails, the array will still be functional, operating in Degraded mode. You can continue to use the array normally because for each Failed disk, the data is stored redundantly on its mirrored pair. However, if both members of a mirrored pair fail, the array will be placed in the Failed state and will not be accessible.

When a RAID 10 disk array is created, the controller will automatically attempt to select the disks for each mirrored pair from a different controller connector (a different cable to a different device enclosure). For example, if four disks selected for the disk array are located on one of the controller's connectors and another four disks selected are located on another of the controller's connectors, the controller will automatically attempt to create each mirrored pair from one disk on each controller connector. In the event of a controller port, cable, or enclosure failure, each mirrored pair will continue to operate in a Degraded mode. Such redundancy requires careful planning when you are determining where to place devices.