A hot spare pool is a collection of slices (hot spares) reserved by DiskSuite to be automatically substituted in case of a slice failure in either a submirror or RAID5 metadevice. Hot spares provide increased data availability for mirrors and RAID5 metadevices. You can create a hot spare pool with either DiskSuite Tool or the command line interface.
When errors occur, DiskSuite checks the hot spare pool for the first available hot spare whose size is equal to or greater than the size of the slice being replaced. If found, DiskSuite automatically resyncs the data. If a slice of adequate size is not found in the list of hot spares, the submirror or RAID5 metadevice that failed is considered errored. For more information, see Chapter 3, Hot Spare Pools.