I'm in the process of standing up a multizone configuration, and one piece I haven't found any recommendations on is how to manage the upgrade process. As far as I can tell, the primary and data zone controllers have to match for proper operations. Does this meant that when I upgrade the primary zone I should just expect the data zone to be out of service until I've also upgraded the data zone controllers, or is there a way to gracefully do the upgrade with minimal service interruption?