Enclosure loss protection is an attribute of . Enclosure loss protection guarantees accessibility to the data on the in an array if a total loss of communication occurs with a single . An example of total loss of communication might be loss of power to the expansion drawer or failure of both (ESMs).
Important:
Enclosure loss protection is not guaranteed if a disk drive has already failed in the array. In this situation, losing access to a expansion drawer and consequently another disk drive in the array causes a double disk drive failure and loss of data.Enclosure loss protection is achieved when you create an array where all of the disk drives that comprise the array are located in different expansion drawers. This distinction depends on the level as shown in the table. If you choose to create an array by using the Automatic method, the software attempts to choose disk drives that provide enclosure loss protection. If you choose to create an array by using the Manual method, you must use the criteria that are specified in the table.
RAID Level | Criteria for Enclosure Loss Protection |
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RAID Level 3, RAID Level 5, or RAID Level 6 |
Make sure that all of the disk drives in the array are located in different expansion drawers. Because a array or a array requires a minimum of three disk drives, enclosure loss protection cannot be achieved if your has less than three expansion drawers. Because a array requires a minimum of five disk drives, enclosure loss protection cannot be achieved if your storage subsystem has less than five expansion drawers. |
RAID Level 1 |
Make sure that each disk drive in a mirrored pair is located in a different expansion drawer. If you make sure that each disk drive in a mirrored pair is located in a different expansion drawer, you can have more than two disk drives in the array within the same expansion drawer. For example, if you were creating a six-disk drive array (three mirrored pairs), you still could achieve enclosure loss protection with only two expansion drawers by specifying that the disk drives in each mirrored pair are located in different expansion drawers. This example shows this concept. Six-disk drive array
Because a RAID Level 1 array requires a minimum of two disk drives, you cannot achieve enclosure loss protection if your storage subsystem has less than two expansion drawers. |
RAID Level 0 | Because a array does not have , you cannot achieve enclosure loss protection. |