Dell PowerVault MD3260 Administrator's Guide - Page 80

Restricted Mappings, dev/sdf at Host 1, Channel 0, Target 0, LUN 2

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Using the following command: # umount filesystemDirectory 2. Run the following command to display multi-pathing topology: # multipath -ll NOTE: Use the multipath -ll command: - If a new LUN is mapped, the new LUN is detected and given a multipathing device node. - If you increased volume capacity, the new capacity is displayed. NOTE: The virtual disk that you want to delete from the mapping. For example, the following information may be displayed: mpath6 (3600a0b80000fb6e50000000e487b02f5) dm-10 DELL, MD32xx [size=1.6T][features=3 queue_if_no_path pg_init_retries 50][hwhandler=1 rdac] \_ round-robin 0 [prio=6][active] \_ 1:0:0:2 sdf 8:80 [active][ready] \_ round-robin 0 [prio=1][enabled] \_ 0:0:0:2 sde 8:64 [active][ghost] In this example, the mpath6 device contains two paths: -- /dev/sdf at Host 1, Channel 0, Target 0, LUN 2 --/dev/sde at Host 0, Channel 0, Target 0, LUN 2 3. Flush the multi-pathing device mapping using the following command: # multipath -f /dev/mapper/mapth_x Where, mapth_x is the device you want to delete. 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. 80

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Using the following command:
# umount filesystemDirectory
2.
Run the following command to display multi-pathing topology:
# multipath -ll
NOTE:
Use the
multipath -ll
command:
–
If a new LUN is mapped, the new LUN is detected and given a multipathing device node.
–
If you increased volume capacity, the new capacity is displayed.
NOTE:
The virtual disk that you want to delete from the mapping. For example, the following information may
be displayed:
mpath6 (3600a0b80000fb6e50000000e487b02f5) dm-10
DELL, MD32xx
[size=1.6T][features=3 queue_if_no_path
pg_init_retries 50][hwhandler=1 rdac]
\_ round-robin 0 [prio=6][active]
\_ 1:0:0:2 sdf 8:80 [active][ready]
\_ round-robin 0 [prio=1][enabled]
\_ 0:0:0:2 sde 8:64 [active][ghost]
In this example, the mpath6 device contains two paths:
-- /dev/sdf at Host 1, Channel 0, Target 0, LUN 2
--/dev/sde at Host 0, Channel 0, Target 0, LUN 2
3.
Flush the multi-pathing device mapping using the following command:
# multipath -f /dev/mapper/mapth_x
Where,
mapth_x
is the device you want to delete.
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.
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