Drawer loss protection is a characteristic of .
In that contain in drawers, a drawer failure can lead to inaccessibility of data on the in a volume group. A drawer might fail because of a loss of power, a failure of an (ESM), or a failure of an internal component within the drawer.
The availability of drawer loss protection for a volume group is based on the location of the drives that comprise the volume group. In the event of a single drawer failure, data on the volumes in a volume group remains accessible if the volume group has drawer loss protection. If a drawer fails and the volume group is drawer loss protected, the volume group changes to , and the data remains accessible.
For achieving drawer loss protection, the drives that comprise a volume group must be located in different drawers with respect to their levels as shown in this table.
RAID Level | Criteria for Drawer Loss Protection |
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RAID Level 3 and RAID Level 5 require a minimum of three drives. Place all of the drives in different drawers for a RAID Level 3 volume group and for a RAID Level 5 volume group to achieve drawer loss protection. Drawer loss protection cannot be achieved for RAID Level 3 and RAID Level 5, if more than one drive is placed in the same drawer. |
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RAID Level 6 requires a minimum of five drives. Place all of the drives in different drawers or place a maximum of two drives in the same drawer and the remaining drives in different drawers to achieve drawer loss protection for a RAID Level 6 volume group. |
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Make sure that each drive in a mirrored pair is located in a different drawer. If you make sure that each drive in a mirrored pair is located in a different drawer, you can have more than two drives of the volume group within the same drawer. For example, if you create a RAID Level 1 volume group with six drives (three mirrored pairs), you can achieve the drawer loss protection for the volume group with only two drawers as shown in this example: Six-drive RAID Level 1 volume group:
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You cannot achieve drawer loss protection because the RAID Level 0 volume group does not have redundancy. |
Note:
If you create a volume group by using the Automatic drive selection method, the storage management software attempts to choose drives that provide drawer loss protection. If you create a volume group by using the Manual drive selection method, you must use the criteria that are specified in the previous table. For more information about how to create volume groups, refer to the Using the Create Volume Group Wizard online help topic.If a volume group already has a Degraded status due to a failed drive when a drawer fails, drawer loss protection does not protect the volume group. The data on the volumes becomes inaccessible.