[ClusterLabs] Antw: snapshoting of running VirtualDomain resources - OCFS2 ?

[Ulrich Windl]

Hi!

IMHO the only clean solution would be this procedure:
1) pause the VMs and cause them to flush their disk buffers, or at least make
sure the writes of the VM guest arrived at the VM host's buffers
2) Cause the VM host filesystem buffers to be flushed to the disk (i.e.: LV)
3) Make a snapshot of the LV on the host
4) Unpause the VM guest
5) backup the LV snapshot on the host
6) delete the LV snapshot on the host

Truely cool would be a solution where a snapshot created inside the VM is
abailable as a snapshot on the host; then you could skip most steps.

Regards,
Ulrich

>>> "Lentes, Bernd" <bernd.lentes at helmholtz-muenchen.de> schrieb am 14.03.2018
um
11:24 in Nachricht
<408515247.33283737.1521023085837.JavaMail.zimbra at helmholtz-muenchen.de>:
> Hi,
> 
> i have a 2-node-cluster with my services (web, db) running in VirtualDomain

> resources.
> I have a SAN with cLVM, each guest lies in a dedicated logical volume with 
> an ext3 fs.
> 
> Currently i'm thinking about snapshoting the guests to make a backup in the

> background. With cLVM that's not possible, you can't snapshot a lustered
lv.
> Using virsh and qemu-img i didn't find a way to do this without a shutdown 
> of the guest, which i'd like to avoid.
> 
> I found that ocfs2 is able to make snapshots, oracle calls them reflinks.
> So formatting the logical volumes for the guests with ocfs2 would give me 
> the possibility to snapshot them.
> 
> I know that using ocfs2 for the lv's is oversized, but i didn't find another

> way to solve my problem.
> 
> What do you think ? I'd like to avoid to shutdown my guests, that's too 
> risky. I experienced already several times that a shutdown can last very
long
> because of problems with umounting filesystems because of open files or user

> connected remotely (on windows guests).
> 
> 
> 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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>  
> 
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