Database Availability Group (DAG) setup in Exchange Server provides full protection and recovery in case of database, network, or server failure. In a DAG, you can have up to 16 mailbox servers hosting a set of databases. This helps provide automatic, database-level recovery in case something happens.
Sometimes, situations arise when you need to split the Database Availability Group (DAG) and move the mailboxes from one availability group to another. Some common situations are: