Creating a Database Availability Group (DAG) in Exchange Server 2013 Using Exchange Management Shell

To configure a Database Availability Group using the EMS, type in the following commands. Replace the example values with the ones that suit your environment:

New-DatabaseAvailabilityGroup –Name DAG1 –WitnessServer WITN01 –WitnessDirectory “C:\DAG” – DatabaseAvailabilityGroupIPAddresses

This command will create the DAG. As part of this process, a computer object, also known as the Cluster Name Object, will automatically be created:

Note In order for this process to complete successfully, you need to have the appropriate permissions on the container in which the object is created. By default this will be the “Computers”-container. However, it is possible that your Active Directory has been reconfigured to use another container/OU as default location for new computer accounts. Have a look at for more information.

Another way to get around the possible issue of permissions is to create the Cluster Name Object (CNO) upfront. This process is also called “pre-staging”. Doing so will allow you to create the object up-front with another account (that has the appropriate rights) so that you don’t run into any issues when configuring your DAG.

To pre-stage the CNO, complete the following tasks:

  1. Open Active Directory Users & Computers, navigate to the OU in which you want to create the object, right-click and select New > Computer:
  2. Right-click the new account and select Properties. Open the Securitytab and add the following permissions:-
  3. Enter a Computer Name and click OK to create the account:
  • Exchange Trusted Subsystem – Full Control
  • First DAG Node (Computer Account) – Full Control

More information on how to pre-stage the CNO can be found here:

Note if your DAG has multiple nodes across different subnets, you will need to assign an IP address in each subnet to the DAG. To do so, you can separate the IP addresses using a comma:

New-DatabaseAvailabilityGroup –Name DAG1 –WitnessServer WIT01 –WitnessDirectory “C:\DAG” – DatabaseAvailabilityGroupIPAddresses,,

Once the command executed successfully, you can now add mailbox servers to the DAG. You will need to run this command for each server you want to add to the DAG:

Add-DatabaseAvailabilityGroupServer –Identity DAG1 –MailboxServer EXH01

Add-DatabaseAvailabilityGroupServer –Identity DAG1 –MailboxServer EXH02

Alternatively, you can also add all/multiple mailbox servers at once to the DAG:

Get-MailboxServer | %{Add-DatabaseAvailabilityGroupServer –Identity DAG1 –MailboxServer $_.Name}

Adding Database Copies

Now that your DAG has been created, you can add copies of mailbox databases to other mailbox servers. For example, to add a copy of EXHDB1 to server EXH2, you would run the following command:

Add-MailboxDatabaseCopy –Identity EXHDB1 –MailboxServer EXH2

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