Dell PowerVault MD3820f - Manual (Page 107)

4. Delete the paths related with this device using the following command:
# echo 1 > /sys/block/sd_x/device/delete
Where, sd_x is the SD node (disk device) returned by the multipath command. Repeat this
command for all paths related to this device. For example:
#echo 1 > /sys/block/sdf/device/delete
#echo 1 > /sys/block/sde/device/delete
5. Remove mapping from c, or delete the LUN if necessary.
6. If you want to map another LUN or increase volume capacity, perform this action from MD Storage
Manager.
NOTE: If you are only testing LUN removal, you can stop at this step.
7. If a new LUN is mapped or volume capacity is changed, run the following command: #
rescan_dm_devs
Restricted Mappings
Many hosts are able to map up to 256 LUNs (0 to 255) per storage partition. However, the maximum
number of mappings differs because of operating system variables, failover driver issues, and potential
data problems. The hosts listed in the table have these mapping restrictions.
If you try to map a virtual disk to a LUN that exceeds the restriction on these operating systems, the host
is unable to access the virtual disk.
Operating System Highest LUN
Windows Server 2003 and Windows Server 2008 255
Linux 255
Guidelines when you work with host types with LUN mapping restrictions:
• You cannot change a host adapter port to a restricted host type if there are already mappings in the
storage partition that would exceed the limit imposed by the restricted host type.
• Consider the case of the Default Group that has access to LUNs up to 256 (0 to 255) and a restricted
host type is added to the Default Group. In this case, the host that is associated with the restricted
host type is able to access virtual disks in the Default Group with LUNs within its limits. For example, if
the Default Group had two virtual disks mapped to LUNs 254 and 255, the host with the restricted
host type would not be able to access those two virtual disks.
• If the Default Group has a restricted host type assigned and the storage partitions are disabled, you
can map only a total of 32 LUNs. Any additional virtual disks that are created are put in the
Unidentified Mappings area. If additional mappings are defined for one of these Unidentified
Mappings, the Define Additional Mapping dialog shows the LUN list, and the Add button is
unavailable.
• Do not configure dual mappings on a Windows host.
• If there is a host with a restricted host type that is part of a specific storage partition, all of the hosts in
that storage partition are limited to the maximum number of LUNs allowed by the restricted host type.
• You cannot move a host with a restricted host type into a storage partition that already has LUNs
mapped that are greater than what is allowed by the restricted host type. For example, if you have a
restricted host type that allows only LUNs up to 31, you cannot move that restricted host type into a
storage partition that has LUNs greater than 31 already mapped.
The Default Group on the Host Mappings tab has a default host type. To change the host type, right-click
on the host and select Change Default Host Operating System from the pop-up menu. If you set the
default host type to a host type that is restricted, the maximum number of LUNs allowed in the Default
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