Thursday, 27 November 2014


This blog deals with how to install Exchange Server 2013 DAG having 2 members. DAG (Database Availability Group) has two networks—one is MAPI Network & another one is Replication Network. MAPI (Microsoft‘s email client software to communicate with Microsoft Exchange) & Replication (copy of a database to another server).


Generally, DAG member runs on two roles, CAS role & Mailbox Server role. However CAS is not required in DAG but sometimes it does not install on same server due to some reason.

Exchange Server 2013 runs on Windows Server 2008 R2 as well as Windows Server 2012. However, for clustering on failover following requirements should be fulfilled:-

  • Enterprise edition of Windows Server 2008 R2 must be installed for supporting Failover Clustering.
  • Must be a Standard edition of Windows Server 2012. 

In order to install DAG member of Exchange 2013:

  • First you have to Install the pre-requisites for Windows Server 2008 R2 or Windows Server 2012 &,
  • Install Exchange server 2013 on the servers.

Let’s take an example of two exchange server having Microsoft windows server 2012 installed namely E15MB1 & E15MB2 and one another server for FSW (file share witness) named as E15FSW.


Since the third server FSW is not an exchange server so you need to make additional permissions. What you have to do is add the ‘Exchange Trusted Subsystem group’ available in AD (active directory) to the 'local Administrator group on the server'.

Here, File Share Witness also requires the File Server feature to be installed. And also make certain that File and Printer Sharing should be enable in the firewall.


The configuration of network for Data Availability Group is necessary for successful DAG network auto-configuration.

In the above Network Interface figure, client server is connected to the & the Exchange server is connected to                                                                                                                                           
Since it is not required for the DAG to have ‘dedicated replication networks’ but if you want so you make sure that DNS registration is disabled in the network interfaces.


E15MB1 & E15MB2 servers had the database which was generated automatically while the set up of Exchange. Now, for replication of database in the DAG you have to execute following tasks:-
  • ‘E15MB1’ having  active mailboxes, has to be moved from the default folder path to the storage volumes dedicated to transaction log files and databases.
  • ‘E15MB2’ having no mailboxes, has to be removed from Exchange.

NOTE-Sometimes all these steps are not required. It depends on your databases existing there.


“CNO is nothing but a computer account object in AD (active directory)”. However CNO is not required everywhere but if you are operating Windows server 2012, you have to create it. Generally there are two ways to create Cluster Name Object . One of them is as:

  >>You can manually create it with the help of AD users. What you need to do is just build a new computer object (name as you desire to give DAG, e.g E15DAG) & then disable the computer account.

The further step is to grant full control for CNO computer account of the first DAG member.  After that navigate to the View menu in active directory Users & enable advanced features option before you can see the Security tab for the computer object.


Now the time comes to create DAG. Just go to Exchange Admin Center & navigate to Servers -> Database Availability Groups and click on + icon for creating a new DAG.

Then a window will pop up mentioned below. You have to fill up details for the new Database Availability Group & after that click on ‘save’.

  • DAG name – should be same which is mentioned earlier.
  • Witness server – required for all DAGs. It is also acc. to the previous given name.
  • Witness directory –optional if not specified a directory Exchange will automatically choose.
  • IP address –required an IP address which is part of the MAPI network. If not specified DAG ‘ll use DHCP instead.


Now you have reached the final step. The DAG has been created but it still does not contain any members. So members need to be added in it.

Go to the new Database Availability Group and click on the icon to manage DAG membership as shown in figure.

Next just add the servers that you desire to join the 'Database Availability Group' and then click ‘Save’. As soon as you click on save it will install and configure the Failover Clustering feature of Windows Server 2012. And new DAG members will be added to the cluster.

As all these action completed, the Database Availability Group will display the members you have added as shown in this window.

So, by undergoing all these procedures you can “Install Exchange 2013 Database Availability Group” with very ease.  All these steps will help you to recover from utter dilemma of Installing DAG.

Product for Exchange Server:

If you are not able to restore mailboxes through DAG under Exchange Server 2013. Also, somehow if Exchange Server 2013 goes down or Exchange database file has been corrupted or goes offline due to any logical reason then I suggest you a third party tool for complete Exchange database recovery. To know more about this tool please follows this URL:

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