Dell PowerVault MD3200i Owner's Manual page 125

Enclosure loss protection is achieved when you create a disk group where all
of the physical disks that comprise the disk group are located in different
expansion enclosures. This distinction depends on the RAID level. If you
choose to create a disk group by using the Automatic method, the software
attempts to choose 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 Table 10-2.
Table 10-2. Criteria for Enclosure Loss Protection
RAID Level Criteria for Enclosure Loss Protection
RAID level 5 Ensure that all the physical disks in the disk group are located in
or RAID level different expansion enclosures.
6
Because a RAID level 5 requires a minimum of three physical disks,
enclosure loss protections cannot be achieved if your storage array has
less than three expansion enclosures. Because a RAID level 6requires a
minimum of five physical disks, enclosure loss protections cannot be
achieved if your storage array has less than five expansion enclosures.
RAID level 1 Ensure that each physical disk in a mirrored pair is located in a
different expansion enclosure. This enables you to have more than
two physical disks in the disk group within the same expansion
enclosure.
For example, if you are creating a six physical disk, disk group (three-
mirrored pairs), you could achieve enclosure loss protection with only
two expansion enclosures by specifying that the physical disk in each
mirrored pair are located in separate expansion enclosures. This
example shows this concept:
• Mirror pair 1—Physical disk in enclosure 1 slot 1 and physical disk in
• Mirror pair 2—Physical disk in enclosure 1 slot 2and physical disk in
• Mirror pair 3—Physical disk in enclosure 1 slot 3and physical disk in
Because a RAID level 1 disk group requires a minimum of two physical
disks, enclosure loss protections cannot be achieved if your storage
array has less than two expansion enclosures.
RAID level 0 RAID level 0 does not have consistency, you cannot achieve enclosure
loss protection.
enclosure 2 slot 1.
enclosure 2 slot 2.
enclosure 2 slot 3.
Configuration: Disk Groups and Virtual Disks
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