Not sure where else to ask this. Rsync'n a running VM?

Hey LQ,

I have a VM running and I'd like to backup the entire thing. I'm curious, what would happen if I had rsync on a cron regularly copy the VM directory? Would that actually work and operate as a backup if I needed it? Or do I need to have this cron script shut the VM down, rsync it, then start it back up?

I'm using Virtualbox if that matters.

Thanks!