You can use a hot spare drive for additional data protection from drive failures that occur in a RAID level 1, 3, or 5 array. If the hot spare drive is available when a drive fails, the controller will use redundancy data to reconstruct the data from the failed drive to the hot spare drive. When you have physically replaced the failed drive, a copyback
A hot spare drive is not dedicated to a specific array but instead is global (can be used for any failed drive in the storage subsystem with the same or smaller capacity). Hot spare drives are only available in a RAID level 1, 3, or 5 array.
Select a drive with a capacity equal to or larger than the total capacity of the drive you want to cover with the hot spare. For example, if you have an 18 GB drive with configured capacity of 8 GB, you could use a 9 GB or larger drive as a hot spare. Generally, you should not assign a drive as a hot spare unless its capacity is equal to or greater than the capacity of the largest drive on the storage subsystem.
The maximum number of SCSI hot spare drives you can create is equal to the number of SCSI drive channels supported by the controller. The maximum number of Fibre Channel