From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Fri, 09 Mar 2012 14:42:50 +0100
From: Zdenek Kabelac <zkabelac@redhat.com>
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Subject: Re: [linux-lvm] Snapshot removal fails first time under RAID
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To: LVM general discussion and development <linux-lvm@redhat.com>
Cc: Philip Boulain <philip.boulain@smoothwall.net>

Dne 7.3.2012 17:22, Philip Boulain napsal(a):
> We have a Debian Wheezy server using mirrored RAID running kernel
> 3.2.0-1-amd64 and LVM version 2.02.88-2. There seems to be an issue
> where snapshot removal fails due to being "in use" the first time, but
> repeating the operation will succeed:
> 
> # lvcreate --size 128M --name testvolume buildturbo64
>   Logical volume "testvolume" created
> # lvcreate --size 128M --snapshot --name testsnap buildturbo64/testvolume
>   Logical volume "testsnap" created
> # lvremove buildturbo64/testsnap
> Do you really want to remove active logical volume testsnap? [y/n]: y
>   LV buildturbo64/testsnap in use: not deactivating
>   Unable to deactivate logical volume "testsnap"
> # lvremove buildturbo64/testsnap
> Do you really want to remove active logical volume testsnap? [y/n]: y
>   Logical volume "testsnap" successfully removed
> # lvremove buildturbo64/testvolume
> Do you really want to remove active logical volume testvolume? [y/n]: y
>   Logical volume "testvolume" successfully removed
> 
> Note that no filesystem is even created here, so it's not mounted or
> anything. That volume group has plenty of free extents (vgdisplay
> excerpt):
> 
>   Alloc PE / Size       52353 / 204.50 GiB
>   Free  PE / Size       66794 / 260.91 GiB
> 
> This is repeatable every time and waiting arbitrary delays between the
> operations makes no difference. There is no difference if the logical
> volume is specified by its device node (/dev/buildturbo64/testsnap).
> 
> Under a *non-RAID* Debian Wheezy VM with an otherwise identical
> configuration, lvremove works first time, as I'd expect.
> 
> Is this a bug, or some form of user error?
> 

Looks like 'famous' watch rule problem with and udev.

Newer version of lvm are trying to a be bit smarted.
But for now easiest would be to remove  'watch' rule being executed on dm
devices if you need urgent solution.
i.e.:

https://bugzilla.redhat.com/show_bug.cgi?id=753105


Zdenek