21.18. Troubleshooting

This section provides solution to common problems users experience during online storage reconfiguration.

Logical unit removal status is not reflected on the host.

When a logical unit is deleted on a configured filer, the change is not reflected on the host. In such cases, lvm commands will hang indefinitely when dm-multipath is used, as the logical unit has now become stale.

To work around this, perform the following procedure:

Procedure 21.7. Working Around Stale Logical Units

Determine which mpath link entries in /etc/lvm/cache/.cache are specific to the stale logical unit. To do this, run the following command:
ls -l /dev/mpath | grep stale-logical-unit
For example, if stale-logical-unit is 3600d0230003414f30000203a7bc41a00, the following results may appear:
```
lrwxrwxrwx 1 root root 7 Aug  2 10:33 /3600d0230003414f30000203a7bc41a00 -> ../dm-4
lrwxrwxrwx 1 root root 7 Aug  2 10:33 /3600d0230003414f30000203a7bc41a00p1 -> ../dm-5
```
This means that 3600d0230003414f30000203a7bc41a00 is mapped to two mpath links: dm-4 and dm-5.

Next, open /etc/lvm/cache/.cache. Delete all lines containing stale-logical-unit and the mpath links that stale-logical-unit maps to.

Using the same example in the previous step, the lines you need to delete are:

/dev/dm-4 
/dev/dm-5 
/dev/mapper/3600d0230003414f30000203a7bc41a00
/dev/mapper/3600d0230003414f30000203a7bc41a00p1
/dev/mpath/3600d0230003414f30000203a7bc41a00
/dev/mpath/3600d0230003414f30000203a7bc41a00p1