Dell PowerVault MD3200i Owner's Manual page 135

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 MDSM, or delete the LUN if necessary.
6 If you want to map another LUN or increase volume capacity, perform this
action from MDSM.
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
8 Use the multipath -ll command to verify that:
• If a new LUN is mapped, the new LUN is detected and given a multi-
pathing device node
• If you increased volume capacity, the new capacity is displayed.
Configuration: Disk Groups and Virtual Disks
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