[libvirt-users] disappeared VM in virsh

[Eric Blake]

On 08/16/2012 08:14 AM, Akendo wrote:
> Hi guys,
> 
> one of my VM has disappeared in libvirtd. I still can see the process
> with ps and the configuration file is as well there. But it is not
> displayed or found with virt-manger/virsh.
> 
> virsh list shows only 4 of 5, but there is no real error message.
> I restarted the daemon without solving the problem. Any idea what to do?

Most likely, this happened because you upgraded libvirt versions, and
the file in /var/run/libvirt/qemu corresponding to the disappearing
guest contained information placed by the older libvirt that the newer
libvirt does not understand.  Could you please locate and send that xml
file for analysis, along with more precise information about your
current libvirt, and whether or not you just recently upgraded libvirt?
 Also, were there any messages in libvirtd.log around the point where
you restarted libvirtd, about unrecognized XML for the disappearing guest?

> 
> Here some info:
> 
> Compiled against library: libvir 0.9.13

Was this self-built from upstream tarballs?  And if so, did you remember
to also apply the RHEL-specific patches that were present on the older
distro version of libvirt?  After all,

> 
> It's a CentOS 6

CentOS 6 ships a version of libvirt based on RHEL, and RHEL 6.3 only
ships with libvirt 0.9.10 + patches.  Some of those patches are
important to preserve if you want a clean upgrade path.

Is the disappearing guest one that you don't mind restarting?  If so,
and my guess about upgrading to self-built libvirt is correct, then
downgrade back to the libvirt that you had previously installed (you
should then see the guest listed again), stop it, then upgrade to the
new libvirt, and now you should be able to start the guest.  And if that
does work, comparing the two versions of /var/run/libvirt/qemu/$dom.xml
(old libvirt vs. new libvirt) may help us identify what specific patch
from the old libvirt is causing grief in the self-built new libvirt.

-- 
Eric Blake   eblake at redhat.com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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