Software Support

Dedicated Hot Spare Considerations
The following considerations apply to dedicated hot spares:
• Considerations for RAID 10, RAID 50, and RAID 60 — If you have created a RAID 10 or RAID 50 virtual disk that
does not fully consume its member physical disks, then you cannot assign a dedicated hot spare to the RAID 10
or RAID 50 virtual disk. Storage Management does not allow you to create RAID 10 and RAID 50 virtual disks
from partial physical disks. You therefore do not encounter this situation if you use Storage Management to
create your virtual disks. If, however, the RAID 10 or 50 virtual disk was created using another application and if
it does contain partial physical disks, then you can assign a dedicated hot spare to the virtual disk.
NOTE: For PERC H700 and PERC H800 controllers, you can assign a dedicated hot spare to RAID 10, RAID
50, and RAID 60.
• Considerations for Multiple Dedicated Hot Spares — From Storage Management version 3.1 onwards, you can
assign more than one dedicated hot spare to a virtual disk.
NOTE: This feature is applicable only on PERC 5 and PERC 6 family of controllers.
Considerations For Hot Spares On PERC S100 And PERC S300
Controllers
For the PERC S100 and PERC 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
is not included in the virtual disk are not rebuilt.
On the PERC S100 and PERC 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 PERC S100 and PERC 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 PERC S100 and PERC S300 controller, the physical disk should
be equal to or greater 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:
• Unassign the hot spare that is assigned as a global hot spare before removing and reassigning a physical disk
that is assigned as a global hot spare, unassign the hot spare before removal and reassign another physical disk
as the global hot spare.
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