xe vbd-param-set uuid=<vbd_uuid> qos_algorithm_type=ionice
xe vbd-param-set uuid=<vbd_uuid> qos_algorithm_params:sched=rt xe vbd-param-set uuid=<vbd_uuid> qos_algorithm_params:class=5 xe sr-param-set uuid=<sr_uuid> other-config:scheduler=cfq
xe pbd-plug uuid=<pbd_uuid>
60