We recently build new mailbox servers on newer hardware and added them to the DAG. Databases were moved off the old servers, connectors copied etc, connectors disabled on the old servers.
Today we planned to power these servers off for 7 days. Was a bit of a disaster - both our CAS servers went to 100%. Slowly recovering now because we powered back on.
I must admit I thought they were dead. Or would they still have been processing client requests? Whats the best way to decomm these servers? Or should I have removed from DAG?