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Re: [Xen-users] Questions on qcow, qcow2 versus LVM

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Subject: Re: [Xen-users] Questions on qcow, qcow2 versus LVM
From: "Matthew Law" <matt@xxxxxxxxxxxxxxxxxx>
Date: Wed, 23 Dec 2009 13:31:04 -0000
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Thanks for the suggestion.  I've seen lots of examples of this on google
and it would seem to be a known and as yet unaddressed bug.  The kernel
seems to be incorrecly tracking the number of LVs which are currently

I can reproduce it on CentOS 5.4 by creating a new LV, adding a disklabel
and paritioning it as linux-swap and then running mkswap on it.  After
that and even though it has never been mounted it cannot be removed
without first rebooting the dom0.  dmsetup claims it is open by one thing
but lsof, fuse, mount, etc do not show it.  Restarting udevd has no effect
on this :-(

Now I am considering two options:

1) If this issue is confined to LVs used for swap disks, perhaps I can
switch to using disk files for domU swap space..?

2) If this isn't confined to LVs used for swap, then perhaps I could have
an opensolaris domU export zvols across NFS or iSCSI back to the dom0 and
use these for each domU system and swap disk? - this sounds a little crazy
to me and performance and load might be unacceptable too.

Are there any other options available?



On Mon, December 21, 2009 1:26 pm, Florian Gleixner wrote:
> I've read somewhere that this is a bug in udev scripts. Stopping or
> restarting udev should do the trick. I've had the problem once ago and
> rebooted. So i cannot say if this really works.

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