User's Manual
Protecting Your Virtual Disk with a Hot Spare 273
A dedicated hot spare can only be assigned to the set of virtual disks that
share the same physical disks. A global hot spare is assigned to all redundant
virtual disks on the controller. A global hot spare must be the same size (or
larger) as the smallest physical disk included in any virtual disk on the
controller.
After you have assigned a global hot spare, any new virtual disks created on
the controller is not protected by the hot spare in either of the following
circumstances:
• The controller is a SCSI controller and the partition size of the disk is
larger than the global hot spare.
• The controller is a SAS controller and the disk size is larger than the global
hot spare.
In this case, you can unassign the global hot spare after creating a new virtual
disk and then assign a new and larger hot spare to cover all redundant virtual
disks on the controller. To determine whether the controller is using SCSI or
SAS technology, see RAID Controller Technology: SCSI, SATA, ATA, and
SAS.
On the PERC 4/SC, 4/DC, 4e/DC, 4/Di, 4e/Si, and 4e/Di controllers, the
virtual disk state is not updated until the controller performs an I/O
operation. This means that when a redundant virtual disk is degraded on one
of these controllers, the hot spare is not activated until the controller
performs an I/O operation. For more information, see I/O and Reboot
Requirements for Detecting Physical Disk Status Changes.
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 cannot assign a dedicated hot spare to the
virtual disk.