The purpose of a DAG is to host one, preferably more, copies of a mailbox database. In the following examples, we will have a look at the different tasks you, as an Administrator, might have to perform.
To execute the following steps, you need access to the Exchange Admin Center or launch the Exchange Management Shell.
We will cover various task related to DAG in this section:
Through the EAC:
Select the database for which you want to add a new copy and select add database copy.
In the add mailbox database copy window, select the mailbox server on which you want to create a new copy.
Set the Activation preference number to 2.
Click on save.
To add a database copy using the Exchange Management Shell, run the following command:
Add-MailboxDatabaseCopy –Identity DB01 –MailboxServer EX03...