In ReadyNAS OS6 devices, you can configure a disk to act as a hot spare. In the event of a failure of an active disk in the volume, the hot spare automatically takes the place of the failed disk.

To use a hot spare, the ReadyNAS must first be in Flex-RAID mode. By default, ReadyNAS operates in X-RAID mode using all available disks.  Once in Flex-RAID mode, add a new disk to an empty slot in the system. This disk is automatically used as a hot spare and no configuration is necessary. The disk that is added must be the same size as or larger than the disks in the volume.

The steps below show the process in more detail.  In this example, a RN4220 with 6 x 4TB disks is used:

To configure a hot spare disk on a ReadyNAS OS6 device:

 1.  To disable X-RAID, click the X_RAID button marked in red.

 2.  When prompted with the pop-up below, click the Yes button.

The green light under the X-RAID button turns grey. This change indicates that X-RAID is disabled and Flex-RAID is enabled

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 3.  Add a new disk to an empty slot.

The disk that is added must be the same size as or larger than the disks in the volume. In this case, we add a new 4TB disk to slot #7.

We are done. No further configuration is needed. If any of the disks in the volume fails, then the unused disk syncs into the volume in place of the failed disk. When the failed disk is then replaced, the replacement disk then acts as the hot spare.

Note.  If you use an expansion chassis (EDA500) with your ReadyNAS, then it is not possible to use a disk in the expansion chassis as a hot spare for a volume in the main unit. It is also not possible to use a disk in the main unit as a hot spare for a volume in the expansion chassis.