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Monday, June 17, 2024

Create DAG (Database Availability Group) in Exchange 2016

Well, Creating DAG is much more simpler as comparing to Exchange 2010,But configuring it properly is the best part to have it efficiently working.

So lets see how to create a 2 node DAG , where most of the Environments are willing to have 2 Dedicated servers for Exchange Server 2016 – (No Roles Anymore – All in One)

Preferred Architecture –

  • Usage of Hardware Load balancers.
  • Combining all Roles in Same Server.
  • No Need of Dedicate Replication Network with highly Available 10g Interfaces.
  • No Need of DAG IP and it shouldn’t have any Administrative Access Point.
  • Usage of Third Witness site to create Active/Active Datacenter (If third site not available keep Witness in Primary Site).

I will describe my environment now.

I have 3 AD sites ,Primary Site And DR-Site has Exchange Servers have a Third Site for Witness.


Get-ExchangeServer | FT name,site -AutoSize


Network Configuration –
I will have my Primary LAN which are Highly Available 10g interfaces which is more sufficient to handle client/replication traffic.

NOTE : If you have 10g Interfaces which is highly Available. Dedicated Replication Network has become optional.Preferred Architecture states to have only one network.


Not Required to pre stage a Cluster CNO object anymore.

  • Now DAG runs without a Cluster Administrative Access Point.

If your DAG Witness Server is not an Exchange Server add Exchange Trusted Subsystem in Local Administrators group

Start – Run – lusrmgr.msc


Now we will  Create a DAG ,

Login to EAC –Servers – Database Availability Groups – Choose New


Specify –

* DAG name

* Witness Server Name

* Witness Location

Now my DAG Configuration is Ready
Add members to it.

Choose Manage DAG Membership


Add your DAG members –


if your Volumes are ReFS – Creating ReFs Volumes for Exchange 2013/2016

To check Default DatabaseAvailabilityGroup FileSystem Type –

Get-DatabaseAvailabilityGroup | FT Name,FileSystem -AutoSize


Change DatabaseAvailabilityGroup FileSystem Type to ReFS –

Set-DatabaseAvailabilityGroup DAG2016 –FileSystem ReFS


To Prevent against application-level split brain syndrome – Enable Datacenter Activation Coordination mode (DAC) –

To check Default DatabaseAvailabilityGroup DatacenterActivationMode Type –

Get-DatabaseAvailabilityGroup | FT Name,DatacenterActivationMode –AutoSize

Change DatabaseAvailabilityGroup DatacenterActivationMode Type to DagOnly –

Set-DatabaseAvailabilityGroup -Identity DAG2016 -DatacenterActivationMode DagOnly


Great !! Now your DAG is ready with Recommended Configuration ! you can start adding Database Copies !!

Satheshwaran Manoharan
Satheshwaran Manoharanhttps://www.azure365pro.com
Award-winning Technology Leader with a wealth of experience running large teams and diversified industry exposure in cloud computing. From shipping lines to rolling stocks.In-depth expertise in driving cloud adoption strategies and modernizing systems to cloud native. Specialized in Microsoft Cloud, DevOps, and Microsoft 365 Stack and conducted numerous successful projects worldwide. Also, Acting as a Technical Advisor for various start-ups.

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  1. Hi Satheshwaran,

    Nice article. well, just one correction i would like to highlight, there is no CAS server role in Exchange 2016. it has been merged as a service in Mailbox Server Role in Exchange 2016.

  2. Hi,

    The article is great, detailed and self explanatory…
    Thanks for all the efforts…

    Currently I have 2013 DAG,

    1) 2 Servers Each having all roles installed on it.
    2) I have barracuda Spam filter too.
    3) I have pointed my mail.company.com and barracuda to DAG IP.. functioning flawlessly from past 2 years.
    4) In case of a server failure the second server takes over automatically, without CAS, HW loadbalancer in picture

    I have some queries..

    Since exchange 2013 creates IP less DAG

    1) Where will clients connect to?
    2) What will happen to Clients… OWA & Outlook?

    I am planning to upgrade my Ex2013 to 2016… a lot depends upon the answer to this..


    • You will need a Hardware Loadbalancer for Client Failover.
      Just works on Layer 4 . No need of additional configuration

      Outlook will disconnect in your case from external world . while it fails over.

  3. PLease let me know what all things to be configured on the second exchange server after installation for making it for DAG configuration. Currently in my environment, we have one exchange server which is fetching mails from Ipage webmail using popcon admin pop connector. I am planning to have a high availability for the exchange server by configuring DAG. Please explain the requirements for the second server for the DAG configuration and how to set up high availability for this scenario. Thanks.

  4. so i want to create a sag group, we only one domain, one exchange 2016 server, so do i just add my new server to the domain ? do i need to install exchange on it first ?? looking for in depth steps from scratch…Thx


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