StorCase Technology Fibre-to-SCSI Single RAID - Manual (Page 90)

78 Configuration
StorCase Technology, Inc. S10C100 User's Guide - Rev. A01
Managing Spares
The controller will automatically reconstruct redundant (fault-tolerant) arrays (RAID 3, RAID
4, RAID 5, and RAID 50, and Mirrored) if an array becomes critical (and a sufficiently-sized
spare drive is available). An array becomes critical when one or more member drives fail.
The user can set up two (2) types of spare drives:
• Dedicated - Available drive that is assigned to a specific array.
• Pool - Available drive that is assigned to the pool, which can provide a spare for
any failed drive in any redundant array.
In addition, if the Dynamic Spares option is enabled and a drive fails, the drive can be replaced
and the controller will rescan the bus; it will then find the new disk drive and automatically start
reconstruction of the array.
The controller will look for a dedicated spare first. If it does not find a sufficiently-sized
dedicated spare, it will then look for a pool spare.
If a reconstruct does not start automatically, it means that there are no valid spares available.
To start a reconstruct, the user must:
1. Replace the failed drive, if no other drive is available.
2. Add the new drive or another available drive as a dedicated spare to the array (or as
a pool spare).
NOTE: Any pool spares added may be used by any critical array, and not necessarily by
the intended array.
Managing Dedicated Spares
Dedicated spares are unused disk drives that are assigned to a specific array. The disk must
be as large as the smallest member in the array. A dedicated spare drive cannot be used in
an array, nor as a pool spare.
Although using a dedicated spare is the most secure way of providing a spare for an array,
it is not very cost-effective keeping an idle drive assigned to the array. An alternative method
is to assign one or more idle drives to the spare pool (refer to section "Managing the Spare
Pool" for further information).