Dell PowerVault MD3820f - Manual (Page 99)

4. Select the appropriate option, you can select:
– View/change current hot spare coverage — to review hot spare coverage and to assign or
unassign hot spare physical disks, if necessary. See step 5.
– Automatically assign physical disks — to create hot spare physical disks automatically for the
best hot spare coverage using available physical disks.
– Manually assign individual physical disks — to create hot spare physical disks out of the selected
physical disks on the Hardware tab.
– Manually unassign individual physical disks — to unassign the selected hot spare physical disks
on the Hardware tab. See step 12.
NOTE: This option is available only if you select a hot spare physical disk that is already
assigned.
5. To assign hot spares, in the Hot Spare Coverage window, select a disk group in the Hot spare
coverage area.
6. Review the information about the hot spare coverage in the Details area.
7. Click Assign.
The Assign Hot Spare window is displayed.
8. Select the relevant Physical disks in the Unassigned physical disks area, as hot spares for the
selected disk and click OK.
9. To unassign hot spares, in the Hot Spare Coverage window, select physical disks in the Hot spare
physical disks area.
10. Review the information about the hot spare coverage in the Details area.
11. Click Unassign.
A message prompts you to confirm the operation.
12. Type yes and click OK.
Hot Spares And Rebuild
A valuable strategy to protect data is to assign available physical disks in the storage array as hot spares. A
hot spare adds another level of fault tolerance to the storage array.
A hot spare is an idle, powered-on, stand-by physical disk ready for immediate use in case of disk failure.
If a hot spare is defined in an enclosure in which a redundant virtual disk experiences a physical disk
failure, a rebuild of the degraded virtual disk is automatically initiated by the RAID controller modules. If
no hot spares are defined, the rebuild process is initiated by the RAID controller modules when a
replacement physical disk is inserted into the storage array.
Global Hot Spares
The MD Series storage arrays support global hot spares. A global hot spare can replace a failed physical
disk in any virtual disk with a redundant RAID level as long as the capacity of the hot spare is equal to or
larger than the size of the configured capacity on the physical disk it replaces, including its metadata.
Hot Spare Operation
When a physical disk fails, the virtual disk automatically rebuilds using an available hot spare. When a
replacement physical disk is installed, data from the hot spare is copied back to the replacement physical
disk. This function is called copy back. By default, the RAID controller module automatically configures
the number and type of hot spares based on the number and capacity of physical disks in your system.
A hot spare may have the following states:
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