Thank you both for the feedback. Wolfgang, I was actually using an incarnation of your script the other day :) Thanks for that. I'll probably backup all my volumes the way Wolfgang does (because it's so simple), but also backup from within the vm on the vms where I have databases. To have a backup for the backup.
Dave Spano ----- Original Message ----- From: "Wolfgang Hennerbichler" <[email protected]> To: "Sebastien Han" <[email protected]> Cc: "Dave Spano" <[email protected]>, [email protected] Sent: Tuesday, April 9, 2013 5:00:41 AM Subject: Re: [ceph-users] Question about Backing Up RBD Volumes in Openstack On Tue, Apr 09, 2013 at 10:09:11AM +0200, Sebastien Han wrote: > So the memory is _not_ saved, only the disk is. Note that it's always hard to > make consistent snapshot. I assume that freezing the filesystem itself is the > only solution to have a consistent snapshot, and still this doesn't mean that > your application's data are consistent , in term of commits for instance with > a database. I don't know which applications do you run but at the end, you > might consider to stop some daemon as well, freeze the fs (to be sure), take > your snapshot, unfreeze, start your daemon. You could reach 100% consistency > with this method… I guess :) I believe in journaling filesystems and their ability to recover from 'crashes' like these. So what I do is just take a snapshot of a running vm. If you re-mount that snapshot (e. g. in a rbd child) the journal replay assures a consistent filesystem. Database systems are designed to recover from power loss, this is nothing different than a power loss. And pg_dump or mysql_dumps (or whatever_dump) are a good habit anyway, if the database is small enough. I've written up how I do ceph backups here: http://www.wogri.at/Ceph-VM-Backup.339.0.html Be aware that disabling rbd_cache in libvirt for now is more safe in terms of stability than enabling it (patches are out there but not in the OS packages yet). > Cheers. my 2c Wolfgang -- http://www.wogri.com
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