[ClusterLabs] Colocation and ordering with live migration

Pavel Levshin lpk at 581.spb.su
Mon Oct 10 08:36:46 EDT 2016

10.10.2016 15:11, Klaus Wenninger:
> On 10/10/2016 02:00 PM, Pavel Levshin wrote:
>> 10.10.2016 14:32, Klaus Wenninger:
>>> Why are the order-constraints between libvirt & vms optional?
>> If they were mandatory, then all the virtual machines would be
>> restarted when libvirtd restarts. This is not desired nor needed. When
>> this happens, the node is fenced because it is unable to restart VM in
>> absence of working libvirtd.
> Was guessing something like that ...
> So let me reformulate my question:
>    Why does libvirtd have to be restarted?
> If it is because of config-changes making it reloadable might be a
> solution ...

Right, config changes come to my mind first of all. But sometimes a 
service, including libvirtd, may fail unexpectedly. In this case I would 
prefer to restart it without disturbing VirtualDomains, which will fail 

The question is, why the cluster does not obey optional constraint, when 
both libvirtd and VM stop in a single transition?

In my eyes, these services are bound by a HARD obvious colocation 
constraint: VirtualDomain should never ever be touched in absence of 
working libvirtd. Unfortunately, I cannot figure out a way to reflect 
this constraint in the cluster.

Pavel Levshin

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