virsh and snapshots with qemu and kvm

Hi,

Is anyone familiar with the status of the snapshot feature with qemu and/or libvirtd?

It appears that only part of it is implemented, only using qcow2, and only with libvirtd/virsh, not directly using qemu. Is this correct?

I have an fc18 system with SSD disks with fc18 guests using raw image format for speed. How much difference is there between qcow2 and raw?

I've read the wiki sites for both qemu and libvirt and neither seem to be documented very well, or I am missing the information.

I'm ultimately trying to create a backup of a guest while it's still running. What is the best way to accomplish this?

Thanks,
Alex