Opening several NBD sockets 'nbd:127.0.0.1:1235' seems dangerous to me. One backup task and easily write to the wrong port - there is no protection? Or how can we guarantee that only one kvm process can write to that NBD device?
> transaction actions=[{'type': 'migrate-async',
> 'destination': 'tcp:127.0.0.1:1234',
> 'id': 'migration'},
> {'type': 'point-in-time-copy-async',
> 'wait-for': 'migration',
> 'device': 'virtio-drive0',
> 'destination-device': 'nbd:127.0.0.1:1235'}]
>
