User's Manual
Considerations for Hot Spare Protection Policy
l The dedicated hot spare protection policy is not applicable to SCSI, SAS/iR, PERC H200, and CERC SATA 6ch/2s controllers.
l RAID 0 does not support assigning hot spares. Also, the protection policy is not applicable for RAID 0.
l For SAS/iR and PERC H200 family of controllers, you can assign only two global hot spares.
l If the status of the virtual disk is displayed as Degraded or Failed because of the hot spare protection policy violation, you must assign the required
number of hot spares (as defined in the protection policies) for the status to be displayed as normal.
l Hot Spare Protection Policy is not applicable to PERC S100 and S300 controllers.
Considerations for Enclosure Affinity
l Enclosure affinity settings for dedicated hot spare are applicable only on PERC 5 and PERC 6 family of controllers.
l Enclosure affinity settings for a global/dedicated hot spare are not automatically set when you upgrade to Dell OpenManage version 6.1.
Enclosure affinity settings for a global/dedicated hot spare are not automatically set when you import a foreign virtual disk.
Considerations for Hot Spares on PERC 4/SC, 4/DC, 4e/DC, 4/Di, 4e/Si, 4e/Di, PERC
5/E, PERC 5/i, PERC 6/E, PERC 6/I, and CERC 6/I Controllers
On the PERC 4/SC, 4/DC, 4e/DC, 4/Di, 4e/Si, 4e/Di, PERC 5/E, PERC 5/i, PERC 6/E, PERC 6/I, and CERC 6/I controllers, assigning a hot spare is equivalent to
assigning a physical disk to replace another physical disk if it fails. If more than one redundant virtual disk resides on the physical disk, then all redundant
portions of the physical disk are rebuilt.
When creating a virtual disk, the physical disks included in the virtual disk can be different sizes. When assigning a hot spare to a RAID 1 or 5 virtual disk, the
hot spare only needs to be the same size (or larger) as the smallest physical disk included in the virtual disk.
This is because when using a PERC 4/SC, 4/DC, 4e/DC, 4/Di, 4e/Si, 4e/Di, PERC 5/E, PERC 5/i, PERC 6/E, PERC 6/I, and CERC 6/I controller, you can assign
physical disks of different sizes to a virtual disk. When you have fully consumed a smaller physical disk with a virtual disk, however, any portion of larger
physical disks that are not consumed by the virtual disk become unusable. Therefore, there is no data on the unused portion of a larger disk that needs to be
rebuilt. A redundant virtual disk is also either striped or mirrored in equal portions across its member physical disks. The amount of data requiring a rebuild is
therefore not larger than the smallest physical disk.
A RAID 10 or 50 virtual disk may include spans that have physical disks of different sizes. In this case, you should identify the span that has the largest "small"
physical disk. The hot spare should be large enough to rebuild this physical disk. For example, if one span has three physical disks that are 60 MB, 60 MB and
40 MB and another span has physical disks that are 60 MB, 60 MB, and 50 MB, then the hot spare must be 50 MB or larger.
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:
l The controller is a SCSI controller and the partition size of the disk is larger than the global hot spare.
l 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:
Property
Definition
Enable Global Hot Spare
Enables the Global Hot Spare Protection Policy.
Minimum Number of Disks
Displays the minimum number of physical disks to be assigned as global hot spares for the
controller.
Severity Level
Displays the severity level that you must assign to the generated alert, if the Global Hot Spare
policy is violated.
Consider Global Hot Spare Policy when determining Virtual
Disk status
Storage Management considers the Global Hot Spare policy to determine the status of the
virtual disk.
The status of the virtual disk is determined by the severity level you specify for this policy.
NOTE: When assigning a global hot spare, consider a physical disk that has higher capacity, which can replace any failed disk in the controller.
NOTE: When rebuilding a physical disk, you need to delete any non-redundant virtual disks (such as RAID 0) that reside on the physical disk before
rebuilding the physical disk.