RAID Level
Criteria for Enclosure Loss Protection
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.
Drawer loss protection
In expansion enclosures that contain drawer-based physical disks, a drawer failure can prevent access to data on the virtual disks of a disk
group.
Drawer loss protection for a disk group is based on the location of the physical disks that comprise the disk group. If there is a single drawer
failure, data on the virtual disks in a disk group remains accessible if drawer loss protection configuration is followed. In such as case, if a
drawer fails and the disk group is protected, the disk group changes to Degraded status and the data remains accessible.
Table 12. Drawer loss protection requirements for different raid levels
RAID Level
Drawer Loss Protection Requirements
RAID Level 6
RAID Level 6 requires a minimum of 5 physical disks. Place all the physical disks in different drawers or
place a maximum of two physical disks in the same drawer and the remaining physical disks in different
drawers.
RAID Level 5
RAID Level 5 requires a minimum of 3 physical disks. Place all the physical disks in different drawers for a
RAID Level 5 disk group. Drawer loss protection cannot be achieved for RAID Level 5 if more than one
physical disk is placed in the same drawer.
RAID Level 1 and RAID Level
10
RAID Level 1 requires a minimum of 2 physical disks. Make sure that each physical disk in a remotely
replicated pair is located in a different drawer. By locating each physical disk in a different drawer, you can
have more than two physical disks of the disk group within the same drawer. For example, if you create a
RAID Level 1 disk group with six physical disks (three replicated pairs), you can achieve the drawer loss
protection for the disk group with only two drawers as shown in this example: 6-physical disk RAID Level 1
disk group:
Replicated pair 1 = Physical disk located in enclosure 1, drawer 0, slot 0, and physical disk in enclosure 0,
drawer 1, slot 0
Replicated pair 2 = Physical disk in enclosure 1, drawer 0, slot 1, and physical disk in enclosure 1, drawer 1,
slot 1
Replicated pair 3 = Physical disk in enclosure 1, drawer 0, slot 2, and physical disk in enclosure 2, drawer 1,
slot 2
RAID Level 10 requires a minimum of 4 physical disks. Make sure that each physical disk in a remotely
replicated pair is located in a different drawer.
RAID Level 0
You cannot achieve drawer loss protection because the RAID Level 0 disk group does not have
consistency.
NOTE:
If you create a disk group using the Automatic physical disk selection method, MD Storage Manager attempts to choose
physical disks that provide drawer loss protection. If you create a disk group by using the Manual physical disk selection method,
you must use the criteria that are specified in the previous table.
If a disk group already has a Degraded status due to a failed physical disk when a drawer fails, drawer loss protection does not protect the
disk group. The data on the virtual disks becomes inaccessible.
Host-to-virtual disk mapping
After you create virtual disks, you must map them to the host(s) connected to the array.
Disk groups, standard virtual disks, and thin virtual disks
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