[Users] Datacenter is down

Hello, after some shutdowns and reboots of my ovirt cluster now the data center is down: - gluster volumes are all UP - all storage (Data/ISO) is inactive - Datacenter is down. I have tried to click on all "activate" buttons I have found but nothing happens. Only one time I got: - failed to activate storage domain - "failed to reconstruct master domain for data center" What can I do now?? Thanks, Mario