Hi, According to the docs on http://libvirt.org/html/libvirt-libvirt.html#virDomainDetachDeviceFlags I ought to be able to do virDomainDetachDeviceFlags( <domain>, <devicexml>, VIR_DOMAIN_DEVICE_MODIFY_LIVE | VIR_DOMAIN_DEVICE_MODIFY_CONFIG); to detach a volume both from a currently running VM instance and permanently from the defined config file. If I actually try that, though, I'm getting this error: libvir: QEMU error : Requested operation is not valid: cannot modify the persistent configuration of a domain The same thing happens whether or not the domain is running and also happens if I leave out the "VIR_DOMAIN_DEVICE_MODIFY_LIVE" part. Does the qemu driver simply not support VIR_DOMAIN_DEVICE_MODIFY_CONFIG yet (libvirt 0.8.1), or is there some other problem here? Guido