Explanation/Reference:
Explanation:
First step: Terminating a Partially Failed Datacenter
When the DAG is in DAC mode, the specific actions to terminate any surviving DAG members in the primary datacenter are as follows:
The DAG members in the primary datacenter must be marked as stopped in the primary datacenter.
Stopped is a state of Active Manager that prevents databases from mounting, and Active Manager on each server in the failed datacenter is put into this state by using the Stop- DatabaseAvailabilityGroup cmdlet.
Reference: Datacenter Switchovers
https://technet.microsoft.com/en-us/library/dd351049(v=exchg.150).aspx