[libvirt-users] disappeared VM in virsh

Eric Blake eblake at redhat.com
Tue Aug 21 21:44:44 UTC 2012


On 08/21/2012 09:38 AM, Akendo wrote:
>> 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.

>>
>> 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.
>>
> Thank you very much for you reply. I upgraded the CentOS 6.3 some days
> ago, but this is a default version of CentOS.

It may be default CentOS, but the fact still remains that CentOS doesn't
ship libvirt 0.9.13; it trails RHEL 6.3 which ships libvirt 0.9.10+patches.

> 
> I restarted the libvirtd without success of finding my VM. But very
> interesting is the fact there is a $dom.xml for my VM. Also is a
> $DOM.pid file.

Yes, the domain is still running, it's just that libvirtd couldn't
figure out how to manage it because of the invalid XML.

> 
> But i found another problem: our system has 12 cores i allowed to use 8
> cores which raise this error message:
> error : virDomainDefParseXML:8871 : Maximum CPUs greater than topology limit

Yep, that would explain it.  Older libvirt silently ignored bugs like
this in the XML, while newer libvirt rejects it; once the XML is
rejected, the VM is no longer listed by libvirt.

> 
> This error message has for some reason suppress in the syslog (lor i
> just didn't read right...) i reduced the amount of CPU to 4. Now it's
> working again.

Yep, that's the correct fix.  Glad we found it for you.

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

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