[CentOS-virt] Backing up a running KVM guest

Thu Mar 26 16:48:36 UTC 2009
Julian Price <centos.org at jul17pri.co.uk>

Kai Schaetzl wrote:
> Another one, although I'm sure that some will loudly protest about it :-)
> I've had excellent results with rsyncing the complete content of Xen VMs 
> to other Xen VMs. It works flawlessly even for MySQL database in full 
> swing. Maybe it makes a difference if you use InnoDB, I'm using MyISAM 
> whereever I can for reasons of speed and robustness. I've rsynced even 
> heavy use servers with no problems (did a lot of tests to make sure the 
> results worked).
> Before doing it this way I checked out the LVM snapshot options (e.g. 
> mount a snapshot and rsync that snapshot) as this is usually recommended 
> but found them not really fitting me. 
> Kai
Are you syncing the disk image as one file via the host, or all the 
files within via the guest?

If you're syncing the image then I'd be interested to know how you do 
that if Xen is the host.  Can you run rsync on Xen?  I thought it was 
just a hypervisor.  Or can Dom0 access the images of other guests to 
rsync them?

If you are just syncing files in the guest (which I wouldn't protest 
about) then the methods are not really comparable because the essential 
point of my approach is that the whole bootable image is backed up, 
which is desirable to some people for lots of reasons.