User's Manual

252 Protecting Your Virtual Disk with a Hot Spare
Considerations for Hot Spares on S100, and S300
Controllers
For the S100, and S300 controllers, a hot spare is assigned to a virtual disk.
When a physical disk fails, only the portion of the physical disk containing
the virtual disk is rebuilt onto the hot spare. Data or space on the physical
disk not included in the virtual disk are not rebuilt.
On the S100, and S300 controllers, individual physical disks may be included
in more than one virtual disk. (Assigning a portion of a physical disk to a
virtual disk does not preclude the remaining portion of the physical disk from
being used by other virtual disks.) Only the virtual disks to which the hot
spare is assigned are rebuilt. When using Storage Management, a disk that is
assigned as a hot spare on a S100, and S300 controller cannot be used as a
member of a virtual disk.
Size Requirements for Global Hot Spares on S100, and S300 Controllers
When assigning a physical disk as a global hot spare on a S100, and S300
controllers, the physical disk should be as large or larger than the largest
physical disk on the controller.
Global Hot Spare Considerations on a SAS 6/iR
The SAS 6/iR controller enables you to assign two global hot spares. The
controller firmware remembers the hot spare assignment even after the
physical disks that you assigned as hot spares have been removed. In other
words, in the case of a disk removal, the firmware may assume that a hot spare
is present when it is not. In this case, the firmware may prevent you from
assigning a new global hot spare as the firmware assumes that a global hot
spare is already assigned.
When a physical disk fails in a redundant virtual disk, the failed disk is rebuilt
onto the hot spare. In this case, the controller firmware reassigns the slot
containing the failed disk as the hot spare. In this circumstance, a disk not
previously assigned as a global hot spare becomes a hot spare through failure
or removal.
To ensure that the controller firmware always has a healthy physical disk as a
global hot spare, do the following: