We currently have a two-node database availability group (DAG) protecting our mailbox databases. Over the weekend, a person or persons unknown shut down the physical server hosting one of the DAG members. No one, including me, noticed any difference-- all our users continued to work normally.
Failover was completely seamless, and neither our Outlook nor OWA nor mobile users contacted me to complain. I only became aware of the problem when I was troubleshooting our back pressure incident.
Exchange 2010 rocks!
