[libvirt-users] how to make consisten backups of guests without stopping them?

Hello. I'd like to backup kvm guests running from lvm partitions on the host without as little downtime as possible, preferably without stopping them. Could libvirt help me with this? Could anybody point me to some documentation? The question is what happens to the filesystem if I snapshot it from the host. LVM is supposed to tell the filesystem to make itself consistent but I don't know how that works if the filesystem is mounted inside the guest. thanks mk