Re: [libvirt-users] snapshots with virsh in a pacemaker cluster
----- Am 15. Okt 2018 um 21:47 schrieb Peter Crowther peter.crowther(a)melandra.com:
Pacemaker always knows where its resources are running. Query it,
stop the
domain, then use the queried location as the host to which to issue the
snapshot?
But can i be sure that the resource starts on the node it was running before ?
IMHO no.
What is if i start the snapshot on node A but the resource starts afterwards on node B ?
Then libvirt on node B does not know it should perform a snapshot.
On Mon, 15 Oct 2018, 20:36 Lentes, Bernd, < [
mailto:bernd.lentes@helmholtz-muenchen.de | bernd.lentes(a)helmholtz-muenchen.de
] > wrote:
> 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
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