This is not the end, there are more features which you will find very interesting such as Co-existent with other roles, Switch/Failovers are much faster, DAG members can be in separate AD sites etc.
The public folder database is not supported by Database Availability Groups.
Below figure gives you a typical DAG overview.
The CAS server re-directs the client requests to the respective Mailbox Databases as shown in the above figure. The database copies are kept in different databases, for e.g. the DB2 is active on the server Mailbox Srv3 and also have a copy of it on different servers(Mailbox Srv1, Mailbox Srv5). The server Mailbox Srv-DR is in a different AD site, however it is still a part of the Database Availability group.
Requirements to Configure DAG
- General Requirement
- Member must be in same AD domain
- Not supported for mailbox role on AD Server
- Hardware requirement
- No special hardware requirement different from mailbox server role
- Software requirement
- Require WFC(failover clustering)
- All the member of a DAG should run the same version OS
- No special requirements, same as previous installation
Switch Over and Failover of Mailbox Databases in DAG:
The server that holds the active copy of database called as the database master. When an administrator moves the active copy from one DAG member to another member is called the database switchover, whereas when an automatic movement happens for database due to the unavailability of active database is called as failover.
Switchover allows the administrator to plan for maintenance on one of the DAG members and also helps in load balancing the active databases across the DAG members.
I will cover more about the DAG configuration and the DAG replication details in coming posts.