– Automatically assign physical disks — to create hot spare physical disks automatically for the best hotspare coverage using available physical disks.– Manually assign individual physical disks — to create hot spare physical disks out of the selected physicaldisks on the Hardware tab.– Manually unassign individual physical disks — to unassign the selected hot spare physical disks on theHardware 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 andclick OK.9. To unassign hot spares, in the Hot Spare Coverage window, select physical disks in the Hot spare physical disksarea.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 RebuildA valuable strategy to protect data is to assign available physical disks in the storage array as hot spares. A hot spareadds 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 spareis defined in an enclosure in which a redundant virtual disk experiences a physical disk failure, a rebuild of the degradedvirtual disk is automatically initiated by the RAID controller modules. If no hot spares are defined, the rebuild process isinitiated by the RAID controller modules when a replacement physical disk is inserted into the storage array.Global Hot SparesThe MD Series Dense storage arrays support global hot spares. A global hot spare can replace a failed physical disk inany virtual disk with a redundant RAID level as long as the capacity of the hot spare is equal to or larger than the size ofthe configured capacity on the physical disk it replaces, including its metadata.Hot Spare OperationWhen a physical disk fails, the virtual disk automatically rebuilds using an available hot spare. When a replacementphysical disk is installed, data from the hot spare is copied back to the replacement physical disk. This function is calledcopy back. By default, the RAID controller module automatically configures the number and type of hot spares based onthe number and capacity of physical disks in your system.A hot spare may have the following states:• A standby hot spare is a physical disk that has been assigned as a hot spare and is available to take over for anyfailed physical disk.• An in-use hot spare is a physical disk that has been assigned as a hot spare and is currently replacing a failedphysical disk.73
