Hi,
Up until recently I've hosted all my stuff (web & mail) on a handful of bare metal servers. Web applications (WordPress, OwnCloud, Dolibarr, GEPI, Roundcube) as well as mail and a few other things were hosted mostly on one big machine.
Backups for this setup were done using Rsnapshot, a nifty utility that combines Rsync over SSH and hard links to make incremental backups.
This approach has become problematic, for several reasons. First, web applications have increasingly specific and sometimes mutually exclusive requirements. And second, last month I had a server crash, and even though I had backups for everything, this meant quite some offline time.
So I've opted to go for KVM-based solutions, with everything split up over a series of KVM guests. I wrapped my head around KVM, played around with it (a lot) and now I'm more or less ready to go.
One detail is nagging me though: backups.
Let's say I have one VM that handles only DNS (base installation + BIND) and one other VM that handles mail (base installation + Postfix + Dovecot).
Under the hood that's two QCOW2 images stored in /var/lib/libvirt/images.
With the old "bare metal" approach I could perform remote backups using Rsync, so only the difference between two backups would get transferred over the network. Now with KVM images it looks like every day I have to transfer the whole image again. As soon as some images have lots of data on them (say, 100 GB for a small OwnCloud server), this quickly becomes unmanageable.
I googled around quite some time for "KVM backup best practices" and was a bit puzzled to find many folks asking the same question and no real answer, at least not without having to jump through burning loops.
Any suggestions ?
Niki