Exchange 2010 database availability group

• DAG is created initially as empty object in Active Directory

DAG is given a unique name and configured for IP addresses (or configured to use)

• When first Mailbox server is added to a DAG
• A failover cluster is formed with name of DAG using Node Majority quorum
• The server is added to the DAG object in Active Directory
• A cluster name object (CNO) for the DAG is created in default Computers container
• The Name and IP address of the DAG is registered in DNS
• The cluster database for the DAG is updated with info about local databases
• the exchange trusted subsystem must have full control to the DAG object in AD

• When second and subsequent Mailbox server is added to a DAG
• The server is joined to cluster for the DAG
• The quorum model is automatically adjusted
• The server is added to the DAG object in Active Directory
• The cluster database for the DAG is updated with info about local databases

You can get more information from : Microsoft Exchange Server 2010: High Availability Deep Dive (including changes introduced by SP1) @

http://www.msteched.com/2010/Europe/UNC401