[gentoo-user] Random failures: lvremove

[Roman Naumann]

Hi,

I'm using LVM, having / and /home as logical volumes and a backup script 
creating a logical snapshot volume of each in the process.

Since I use gentoo (comming from arch), my backup script fails rather often 
with the error message 'Can't remove open logical volume <volume>'. The script 
worked fine on arch before. The partition setup did not change.

Sometimes it works fine, sometimes it just fails.
As a workaround, I let the script just lvremove the snapshot three times with 
5 seconds sleeping between the tries and the overall success rate for the 
script improved...
The chance is about 40% lvremove succeeds at a given time and doesn't seem to 
in- or decrease when calling lvremove successively with a five second delay, 
though if it fails once, it tends to fail again more often if called within 
the next two or three seconds.

Here is an example of the command failing once more after the backup script 
aborted. The second time it works. I did NOTHING but the commands listed below 
in these 30 seconds or so: (note: dmsetup says "open: 0" in the first place!)

kira namor # dmsetup info -c vg-snap_root
Name             Maj Min Stat Open Targ Event  UUID                                                                
vg-snap_root     253   5 L--w    0    1      0 LVM-
ayg5GD1dYyrkkan1pLa8WszI7UrQpy9YE2ynOTtHoSNckKdehm3XMIgkw7p8z69X
kira namor # lvremove /dev/vg/snap_root 
  Can't remove open logical volume "snap_root"
kira namor # lsof /dev/vg/snap_root 
kira namor # fuser -a /dev/vg/snap_root 
/dev/vg/snap_root:
kira namor # lvremove /dev/vg/snap_root
Do you really want to remove active logical volume snap_root? [y/n]: y
  Logical volume "snap_root" successfully removed

What I tried so far was:
-> calling: lvchange -an $SNAP_PARTITION #fails iff lvremove fails
-> updating to lvm2-2.02.56-r3 and updating the initramfs #fixes nothing

I have no idea what causes this random behavior.
Help much appreciated.

Regards,
Roman Naumann