As is already well documented, we find that we need cache='none' to support migration, otherwise there is the chance of a hang and/or failure to pivot. However we prefer the default of cache=writethrough when operating in production. Our practice is to 'shutdown' the VM completely make the change with virsh edit, then restart. Then we have to repeat the process to revert back once we migrate. Is it possible to change that function on the fly and avoid the shutdown/start process? Note: we have had inconsistent results with virsh edit first and then a reboot. A complete shutdown seems to be necessary, but I am hoping there is some other procedure available. Our images are all qcow2 (1.1) Sincerely, W Kern PixelGate Networks