Hot spare drives are reserved drives assigned to protect redundant arrays in the event of a drive failure. If a drive fails in a redundant array protected by a hot spare, the array is rebuilt using the reserved hot spare. The hot spare replaces the failed drive as long as the spare is of equal or larger size than the drive it needs to replace.
On advanced feature set controllers, the same hot spare can be used to replace a failed drive in multiple arrays. For this to occur, the hot spare must contain a free segment at least as large as the corresponding segment on the most recently failed drive.
On some controllers, a hot spare can be assigned to protect a single array or a global hot spare can be assigned to protect all the arrays on the controller. Advanced feature set controllers support global or dedicated. Classic feature controllers and HostRAID controllers support global only.
Some controllers do not support hot spare capability.
Review your controller documentation to confirm that your controller supports
this feature.