[libvirt-users] snapshots with virsh in a pacemaker cluster

Lentes, Bernd bernd.lentes at helmholtz-muenchen.de
Mon Oct 15 19:29:59 UTC 2018


Hi,

i have a two node cluster with virtual guests as resources.
I'd like to snapshot the guests once in the night and thought i had a procedure.
But i realize that things in a cluster are a bit more complicated than expected :-))

I will shutdown the guests to have a clean snapshot.
I can shutdown the guests via pacemaker.
But then arises the first problem:

When i issue a "virsh snapshot-create-as" libvirt needs the domain name as a parameter.
but libvirt does not know the domains any longer. When the guests are shutdown a "virsh list --all"
on both nodes does not show any domain.

A look in the respective resource agent VirtualDomain explains why:
The domain is started with virsh create:

"# The 'create' command guarantees that the domain will be
# undefined on shutdown, ...

OK: Now i could of course define all domains with a virsh define.

But then i have immediately the next problem. Now i'd create the snapshots with
"virsh snapshot-create-as" and starts the domains afterwards via cluster.
But let's assume i issue that on node 1 and some guests are started afterwards via pacemaker on node 2.
I can't predict on which node the guests are starting.

Then i don't get a snapshot, right ?

What to do ?

Bernd



-- 

Bernd Lentes 
Systemadministration 
Institut für Entwicklungsgenetik 
Gebäude 35.34 - Raum 208 
HelmholtzZentrum münchen 
[ mailto:bernd.lentes at helmholtz-muenchen.de | bernd.lentes at helmholtz-muenchen.de ] 
phone: +49 89 3187 1241 
fax: +49 89 3187 2294 
[ http://www.helmholtz-muenchen.de/idg | http://www.helmholtz-muenchen.de/idg ] 

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