What is enclosure loss protection?

Enclosure loss protection is an attribute of a . Enclosure loss protection guarantees accessibility to the data on the ??in a disk group if a total loss of communication occurs with a single disk expansion enclosure. This loss could be a loss of power to the disk expansion enclosure or failure of both .

Important: Enclosure loss protection is not guaranteed if a disk physical disk failure has already failed in the disk group. In this situation, losing access to a disk expansion enclosure (and consequently another disk physical disk in the disk group) will cause a double disk physical disk failure and a loss of data.??

Enclosure loss protection is achieved when you create a disk group where all of the disk physical disks that comprise the disk group are located in different disk expansion enclosures. This distinction depends on the ??level as shown in the table. If you choose to create a disk group by using the Automatic method, the software tries to choose disk physical disks that provide enclosure loss protection. If you choose to create a disk group by using the Manual method, you must use the criteria specified in the table.

RAID Level

Criteria for Enclosure Loss Protection
 or  or

Make sure that all of the disk physical disks in the disk group are located in different disk expansion enclosures.

Note: Because a RAID 3 disk group or RAID 5 disk group requires a minimum of three disk physical disks, enclosure loss protection cannot be achieved if your has less than three disk expansion enclosures. Because a RAID 6 disk group requires a minimum of five disk physical disks, enclosure loss protection cannot be achieved if your storage array has less than five disk expansion enclosures.

Make sure that each disk physical disk in a mirrored pair is located in a different disk expansion enclosure.

If you make sure that each disk physical disk in a mirrored pair is located in a different disk expansion enclosure, you will be able to have more than two disk physical disks in the disk group within the same disk expansion enclosure. For example, if you were creating a six-disk physical disk disk group (three mirrored pairs), you could still achieve enclosure loss protection with only two disk expansion enclosures by specifying that the disk physical disks in each mirrored pair are located in different disk expansion enclosures. The example shows this concept.

Six-physical disk RAID 1/10 disk group

  • Mirror pair 1 = Physical Disk in enclosure 1, slot 1, physical disk in enclosure 2, slot 1
  • Mirror pair 2 = Physical Disk in enclosure 1, slot 2, physical disk in enclosure 2, slot 2
  • Mirror pair 3 = Physical Disk in enclosure 1, slot 3, physical disk in enclosure 2, slot 3

Note: Because a RAID 1/10 disk group requires a minimum of two physical disks, you cannot achieve enclosure loss protection if your storage array has less than two expansion enclosures.
Because a RAID 0 disk group does not have , you cannot achieve enclosure loss protection.