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[linux-lvm] snapshots can't be deactivated

Hello list,

I have a strange behaviour on my snapshots.
I got a Ubuntu Server 7.04 with LVM2 setup:

lvm> version
  LVM version:     2.02.06 (2006-05-12)
  Library version: 1.02.08 (2006-07-17)
  Driver version:  4.11.0

I have two logical volumes I want to make snapshots of every night:

/dev/vg0/home with XFS
/dev/vg0/opt with XFS

These snapshots will be mounted read-only under /backup

So in principle the steps to achieve this should be:

 - unmount the snapshot from yesterday (umount /backup/home)
 - discard the snapshot from yesterday (lvremove -f
 - freeze the filesystem (xfs_freeze -f /dev/vg0/home)
- create the snapshot (lvcreate --snapshot --size 20G --name daily-snap-home -v /dev/vg0/home)
 - unfreeze the filesystem (xfs_freeze -u /dev/vg0/home)
- mount the new snapshot ro (mount -oro,nouuid /dev/vg0/daily-snap-home /backup/home)

I wrote a script for that with some error checking too. But sometimes this doesn't work. The problem seems to be that the snapshot isn't removed even if "lvremove -f " sais it is removed. I got the following error message when I then recreate the snapshot:

root konrad:~# ./create-snapshot-home.sh
+ /sbin/lvs
  LV              VG   Attr   LSize   Origin Snap%  Move Log Copy%
  daily-snap-home vg0  swi-ao  20.00G home     0.00
  daily-snap-opt  vg0  swi-ao  20.00G opt      0.08
  home            vg0  owi-ao 100.00G
  opt             vg0  owi-ao 100.00G
  root            vg0  -wi-ao  10.00G
  video           vg0  -wi-ao 800.00G
+ /bin/umount -f /backup/home
+ /sbin/lvdisplay
+ grep /dev/vg0/daily-snap-home
                         /dev/vg0/daily-snap-home [active]
  LV Name                /dev/vg0/daily-snap-home
+ [ 0 -eq 0 ]
+ [ -b /dev/mapper/vg0-daily--snap--home ]
+ /sbin/lvremove -f /dev/vg0/daily-snap-home
  Logical volume "daily-snap-home" successfully removed
+ sleep 5
+ [ -b /dev/mapper/vg0-daily--snap--home ]
+ [ 0 -eq 0 ]
+ /usr/sbin/xfs_freeze -f /home
+ [ 0 -eq 0 ]
+ /sbin/lvcreate --snapshot --size 20G --name daily-snap-home -v /dev/vg0/home
    Setting chunksize to 16 sectors.
    Finding volume group "vg0"
    Archiving volume group "vg0" metadata (seqno 116).
    Creating logical volume daily-snap-home
    Creating volume group backup "/etc/lvm/backup/vg0" (seqno 117).
    Found volume group "vg0"
    Creating vg0-daily--snap--home
    Loading vg0-daily--snap--home table
    Resuming vg0-daily--snap--home (254:5)
    Clearing start of logical volume "daily-snap-home"
    Found volume group "vg0"
  LV vg0/daily-snap-home in use: not deactivating
  Couldn't deactivate new snapshot.
+ /usr/sbin/xfs_freeze -u /home
+ /bin/mount -oro,nouuid /dev/vg0/daily-snap-home /backup/home
mount: you must specify the filesystem type

I don't know why this happens. The script will work perfectly 3 out of 5 times. But sometimes it comes up with the error above.

Are my steps right in principle? Did I forget to do something before or after removing?

Thanks and kind regards


Falko Zurell
Head of Application Management

/i-d media AG
Ohlauer Stra├če 43
D-10999 Berlin

Tel +49 (0)30 - 2 59 47 - 357
Fax +49 (0)30 - 2 59 47 - 471


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