Learn About Using Hot Spare Drives for Data Protection

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 operation occurs from the hot spare drive to the replaced drive. Your storage subsystem logical drive remains online and accessible while you are replacing the failed drive, since the hot spare drive is automatically substituting for the failed drive.

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.

Hot Spare Drive Capacity Considerations

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.

How Many Hot Spare Drives Can You Create?

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 hot spare drives depends on the controller model, but is typically 15.