[Ocfs2-users] Can't delete LV snapshot after mounting

[Armin Wied]

Hello group!

I'm pretty new to ocfs2 and clustered file systems in general.
I was able to set up a 2 node cluster (CentOS 5.4) with ocfs2 1.4.4 on DRBD
on top of a LVM volume.

Everything works like a charm and is rock solid, even under heavy load
conditions, so I'm really happy with it.

However, there remains one little problem: I'd like to do backups with
snapshots. Creating the snapshot volume, mounting, copying and dismounting
works like expected. But I can't delete the snapshop volume after it was
mounted once.

What I do is:

lvcreate -L5G -s -n lv00snap /dev/vg00/lv00
tunefs.ocfs2 -y --cloned-volume /dev/vg00/lv00snap
mount -t ocfs2 /dev/vg00/lv00snap /mnt/backup

(copy stuff)

umount /mnt/backup
lvremove -f /dev/vg00/lv00snap

lvremove fails, saying, that the volume is open. Checking with lvdisplay it
tells me "# open" is 1.
And that's the funny thing: After creating the snapshot volume, # open is 0,
what's not a surprise. After mounting the volume, # open is 2 - which is the
same for the other ocfs2 volume and makes sense to me, as there are 2 nodes.
But after unmounting the snapshot volume, the number decreases to 1, not to
0 so LVM consideres the volume still open.

I also tried mounting read only and/or adding "--fs-features=local" to
tunefs.ocfs2 without success. In the moment I have to reboot the node to be
able to remove the snapshot.

So what am I doing wrong?

Thank's a lot for any hint!

Armin