[ClusterLabs] snapshoting of running VirtualDomain resources - OCFS2 ?

[Gang He]

Hello Lentes,


>>> 
> 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.
Yes, OCFS2 reflink can meet your requirement, this is also why ocfs2 introduces file clone. 

> 
> 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).
Just one comments, you have to make sure the VM file integrity before calling reflink.

Thanks
Gang

> 
> 
> Bernd
> 
> -- 
> 
> Bernd Lentes 
> Systemadministration 
> Institut für Entwicklungsgenetik 
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