[openstack][cinder] volume_copy_bps_limit

Hello stackers, I am using cinder netapp nfs driver and I have vm performances problems during the backup of volumes. My backup tool make snapshots of volumes, then, on compute notes, it use virt-convert for creating a volume backup on another nfs backend using a different vlan. But during the virt-convert a lot of read are done on netapp and my virtual machines become very slow. I am asking if volume_copy_bps_limit can help me to mitigate. Please, anyone could help me ? Ignazio