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Re: Random libvirt hangs


On Mon, Mar 12, 2012 at 02:17:49PM -0400, David Kranz wrote:
> In the spirit of Jay's message, we have a long-running cluster
> (diablo/kvm) where about once every 3-4 weeks a user will complain
> that she cannot connect to a vm. Examining the compute node shows
> that libvirt-bin is hung. Sometimes restarting this process fixes
> the problem. Sometimes it does not, but rebooting the compute node
> and then the vm does. I just heard from people in my company
> operating another cluster (essex/kvm) that they have also seen this.
> I filed a bug about a month ago
> https://bugs.launchpad.net/nova/+bug/931540
> Has any one been running a kvm cluster for a long time with real
> users and never seen this issue?

There have been various scenarios which can cause libvirtd to hang in
the past, but that bug report doesn't have enough useful data to
diagnose the issue. If libvirtd itself is hanging, then you need to
attach to the daemon with GDB, and run 'thread apply all bt' to collect
stack traces across all threads. Make sure you have debug symbols
available when you do this.

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