[Users] Designate Master Storage Domain

Is there any method of designating which domain should be the master storage domain or forcibly changing the role to a different storage domain? EG: Given the following example Storage Domain A (Master) --> NFS --> Storage Server 1 Storage Domain B --> NFS --> Storage Server 2 One wants to do maintenance to Storage Server 1 but in doing so the Master storage domain is hosted from Storage Server 1. Thus the net result of taking down Storage Server 1 is that one must also take down Storage Server 2. Thus we know we must shut down VM's from Storage Domain A to maintenance Storage Server 1. Suppose however that VM's are running that we don't want to shut down and are hosted from Storage Domain B via Storage Server 2. We would want to be able to promote Storage Domain B to Master so that we can take down Storage Domain A to do maintenance to Storage Server 1. Once we are done with maintenance to Storage Server 1 we can bring Storage Domain A back on line, re-designate it as Master if desired and bring it's VM's back online. I know I have seen this occur automatically to a point when a Storage Domain goes missing that is the Master Domain but I have not noted any manual method of doing so given the above scenario. - DHC