Configuration: Disk Groups and Virtual Disks 125
Host-to-Virtual Disk Mapping
After you create virtual disks, you must map them to the host(s) connected to
the array.
Guidelines to configure host-to-virtual disk mapping:
• Each virtual disk in the storage array can be mapped to only one host or
host group.
• Host-to-virtual disk mappings are shared between controllers in the
storage array.
• A unique LUN must be used by a host group or host to access a virtual disk.
• Each host has its own LUN address space. MDSM permits the same LUN
to be used by different hosts or host groups to access virtual disks in a
storage array.
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 (3-
mirrored pairs), you can 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. For
example:
• Mirror pair 1—Physical disk in enclosure 1, slot 1 and physical disk in
enclosure 2, slot 1.
• Mirror pair 2—Physical disk in enclosure 1, slot 2 and physical disk in
enclosure 2, slot 2.
• Mirror pair 3—Physical disk in enclosure 1, slot 3 and physical disk in
enclosure 2,slot 3.
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 Because RAID level 0 does not have consistency, you cannot achieve
enclosure loss protection.
Table 9-2. Criteria for Enclosure Loss Protection
(continued)
RAID Level Criteria for Enclosure Loss Protection
book.book Page 125 Friday, September 23, 2011 2:46 PM
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