Exchange Server 2013 - Configuring Database Availability Group (DAG)

Article
1/17/2024

EXCHANGE 2013 - CONFIGURING DATABASE AVAILABILITY GROUP (DAG)

A database availability group (DAG) is a collection of servers that provides the infrastructure for replicating and activating database copies. The DAG uses continuous replication to each of the passive database copies within the DAG.

In this article I will show how to configure DAG and fault tolerance testing by DAG.

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In my LAB, I use five computers:

- DC2012: Domain Controller (domain mcthub.local) running Windows Server 2012

- EXCHANGE1 and EXCHANGE2: Domain Member running Windows Server 2012 and Exchange Server 2013 (Mailbox Role and Client Access Role)

- FILESERVER: Domain Member running Windows Server 2012 (File Share Witness Server). I recommend that you configure the witness server on a Client Access server in the Exchange Server organization. The additional load on the server is minimal, and it is already under the control of the Exchange Server management group. The witness server does not need to run the same version of Windows Server as the members of the DAG. The file share witness also requires the File Server feature installed

- CLIENT1: Domain Member running Windows 8 and Outlook 2013

Because the file share witness server is not an Exchange server, some additional permissions are required. The Exchange Trusted Subsystem group in Active Directory must be added to the local Administrators group on the file share server.

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And you should verify that File and Printer Sharing is allowed through the firewall. Open Windows Firewall (FIREWALL.CPL) - Select "Allow an app or feature through Windows Firewall"

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- Verify File and Printers Sharing is selected- OK

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Pre-stage the cluster network object for a DAG

- On DC2012, in Server Manager, click Tools, and then click Active Directory Users and Computers. On the menu bar, click View, and then click Advanced Features.

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- Create a Computers Account

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- Type an arbitrary name (DAG1) - OK

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- On Security tab, grant the computer account for the first DAG member (EXCHANGE1) and the Exchange Trusted Subsystem group ***Full Control ***

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- Click OK

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- Then disable the computer account. http://mcthub.com/images/ContentLab/DAG-En_files/image010.jpg

Create a DAG and add mailbox servers to the DAG

- Switch to EXCHANGE1. Open Internet Explorer, and type https://exchange1.mcthub.local/ecp, and then press Enter. Navigate to servers - databases, You observe the system, I have two mailbox servers included*** EXCHANGE1*** and EXCHANGE2. EXCHANGE1 hosting Mailbox Database named Mailbox Database 1

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- Now I will create a DAG. Navigate to servers - database availability groups, Click the New (+) icon

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-Enter the following details for the new DAG and Click Save when you have entered all of the required details

DAG name – this should match the comnputer account name you pre-staged earlier

Witness server – this is required for all DAGs

Witness directory – this is optional. If you do not specify a directory Exchange will choose one for you.

IP address – the DAG requires an IP address on each IP subnet that is part of the MAPI network. If you do not specify IP addresses the DAG will use DHCP instead.

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- After the DAG has been created it still does not contain any members. These need to be added next.

click the icon to manage DAG membership

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- Click ***Add (+) ***icon

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- Select both servers, then click ***Add ***button

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- Click ***OK ***button

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- Verify membership of the DAG and click ***Save ***button

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- Note that this might take some time, so please wait.

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- Click Close button when finished.

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- Done, DAG has been created successfully http://mcthub.com/images/ContentLab/DAG-En_files/image021.jpg

Create a mailbox database copy

- Navigate to servers - databases. Refresh the view- Click Mailbox Database 1, Click More (…) - click Add database copy.

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- Click ***Browse ***button

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- Select server EXCHANGE2 - Click OK button

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- Click ***Save ***button

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- Wait until the saving completes successfully

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- Then click close when finished

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- Verify successful completion of copying a database. In databases tabs, click Refresh, and wait until the details pane shows Mailbox Database 1\EXCHANGE2 as Passive Healthy. This might take several minutes and up to several hours depending on the size of the database. Make sure that the Status displays Healthy and the Content index state also displays Healthy. Then click cancel. Note that this might take some time, so please wait.

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- Or you can also use Get-MailboxDatabaseCopyStatus to check the database copy health

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- You can also use the below command to check the synchronization process

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Verify successful completion of passive database

- To move Mailbox Database 1 to EXCHANGE2 I can simply highlight it and then review the status of the database copies. Note that in this case the passive copy on EXCHANGE2 is healthy, with no copy queue length issues and a healthy content index state as well.

Under those conditions we can proceed with the switchover by clicking the link to Activate the database copy

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- Click Yes to confirm the action

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- Then a progress bar let’s you know when the operation is complete, so please wait

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- Click Close when finished

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- I can see that Mailbox Database 1 is now active on server EXCHANGE2..

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- Or you can also use Get-MailboxDatabaseCopyStatus to check the result

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