[cinder] Disable Availability Zone

Hello Stackers, For legacy purposes, we've got an Availability Zone running that's not to be used for new workload any more. Within Nova one could simply disable Compute Nodes (and that's what we did) ensuring no Compute Instances get scheduled. But, how about Cinder? How can we keep current workload running within a certain AZ, but ensure no new workload gets accepted? Thanks! Cheers, Kees