Accidentally sent to OP only. This has been with 0.8.7 on CentOS 6 CR that Ive had the problem. ---------- Forwarded message ---------- From: "Trey Dockendorf" <treydock(a)gmail.com&gt; Date: Oct 24, 2011 12:31 AM Subject: Re: [libvirt-users] Unable to acquire lock To: "Jatin Kumar" <cs5090243(a)cse.iitd.ernet.in&gt; On Mon, Oct 24, 2011 at 12:05 AM, Jatin Kumar <cs5090243(a)cse.iitd.ernet.in&gt;wrote: I've run into this a few times when a snapshot hangs. Unfortunately I can't offer much advice on why it happens, but increasing log verbosity may help troubleshoot it. These are the relevant lines I use in /etc/libvirt/libvirtd.conf log_level = 2 log_filters="2:remote 2:event" log_outputs="2:file:/var/log/libvirt/libvirtd.log" Be careful with level 1 alerts...I generated a 100GB text log in 3 days. To fix that problem and unlock a VM, you need to kill libvirt, remove the PID files and start libvirt # service libvirtd stop # rm -rfv /var/run/libvirt # service libvirtd start More information here, https://bugzilla.redhat.com/show_bug.cgi?id=676205 - Trey