Host-to-virtual disk mapping, Host-to-virtual disk, Mapping – Dell POWERVAULT MD3600I User Manual

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Drawer loss protection for a disk group is based on the location of the physical disks that comprise the disk group. In the
event of a single drawer failure, data on the virtual disks in a disk group will remain 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.
To configure your storage for drawer loss protection, make sure that physical disks that are part of a disk group are
located in different drawers with respect to their RAID levels, as shown in the following table.

Table 5. Drawer Loss Protection Requirements for Different RAID Levels

RAID Level

Drawer Loss Protection Requirements

RAID Level 6

RAID Level 6 requires a minimum of five physical disks. Place all of 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 three physical disks. Place all of 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 two 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: Six-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 four 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 redundancy.

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.
The following are the 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. MD Storage Manager permits the same LUN to be used by different

hosts or host groups to access virtual disks in a storage array.

All operating system do not have the same number of LUNs available.

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