LSI MegaRAID Enterprise 1600 - Manual (Page 25)

Chapter 2 Introduction to RAID 11
Hot Spares
A hot spare is an extra, unused disk drive that is part of the disk subsystem. It is usually in standby
mode, ready for service if a drive fails. Hot spares permit you to replace failed drives without
system shutdown or user intervention.
MegaRAID implements automatic and transparent rebuilds using hot spare drives, providing a high
degree of fault tolerance and zero downtime. MegaRAID RAID Management software allows you
to specify physical drives as hot spares. When a hot spare is needed, the MegaRAID controller
assigns the hot spare that has a capacity closest to and at least as great as that of the failed drive to
take the place of the failed drive.
Important
Hot spares are employed only in arrays with redundancy, for
example, RAID levels 1, 3, 5, 10, 30, and 50.
A hot spare connected to a specific MegaRAID controller can
only be used to rebuild a drive that is connected to the same
controller.