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October 9, 2009 / dw

DAG (Database Availability Group)

 

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Create a Database Availability Group – http://technet.microsoft.com/en-us/library/dd351172(EXCHG.140).aspx?v=14.0.639.11&t=exchgf1

This wasn’t as straight forward as I thought. I had some issues with this, which was partly related to an under powered lab and the fact we really need a third server for the DAG.

I wound up with two Exchange 2010 Servers and a File Share witness server that was a Windows 2008 file share.

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I had to specify the Witness Directory because the server I was using was not an Exchange Server.

The following combinations of options and behaviors are available when creating a new DAG:

· You can specify only a name for the DAG and leave the Witness Server and Witness Directory check boxes cleared. In this scenario, the wizard will search for a Hub Transport server that doesn’t have the Mailbox server role installed. It will automatically create the default directory and share on that Hub Transport server and use that server as the witness server.

· You can specify a name for the DAG, the witness server that you want to use, and the directory you want created and shared on the witness server.

· You can specify a name for the DAG and the witness server that you want to use, and leave the Witness Directory check box cleared. In this scenario, the wizard will create the default directory on the specified witness server.

· You can specify a name for the DAG, leave the Witness Server check box cleared, and specify the directory you want created and shared on the witness server. In this scenario, the wizard will search for a Hub Transport server that doesn’t have the Mailbox server role installed, and it will automatically create the specified directory on that server, share the directory, and use that Hub Transport server as the witness server.

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Well, I found out you must add the full path.

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Add the servers to the DAG.

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This failed because I tried to put the FSW on one of the two Exchange servers. A third Exchange server would be the best. A HUB server without the mailbox roll is recommended.

Now I tried to Creating a Database copy:

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I tried to get around the 3 server by adding a server not in the domain. It didn’t work.

I then created a server just for file sharing.

On the properties of each DAG I then changed the FSW path.

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I created the share on FSW.lab.dw (which you should NOT do by the way. Let Exchange set it up and all permissions will be correct. If Exchange can not set it up, something else is wrong, read on)

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I had some problems with the DAGs from this point, so I removed all DAGs and created new. I thought much of my problem was from the fact I missed this statement. “If the witness server you specify isn’t an Exchange 2010 server, you must add the Exchange Trusted Subsystem universal security group to the local Administrators group on the witness server.” So I started trouble shooting.

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I then received this error;

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OR

—————————-

Summary: 1 item(s). 0 succeeded, 1 failed.
Elapsed time: 00:00:00

Lab-DAG-1-FSW
Failed

Error:
Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))

Warning:
Specified witness server FSW.LAB.DW is not an Exchange server, or part of the Exchange Servers security group.

Warning:
An unexpected error has occurred and a Watson dump is being generated: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))

Exchange Management Shell command attempted:
New-DatabaseAvailabilityGroup -Name ‘Lab-DAG-1-FSW’ -WitnessServer ‘FSW.LAB.DW’ -WitnessDirectory ‘c:Lab-DAG-1-FSW’

Elapsed Time: 00:00:00

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After verifying it was the non-exchange server causing the problem, (I could create a new DAG on the Exchange servers) here is what I tried:

I disabled the Fire Wall on The FSW servers.
I added the server to group "Exchange Servers".
I added the computer account to Exchange Trusted Subsystem group in AD.

I added the Exchange Trusted Subsystem group to the BuiltinAdministrators group of the domain.

I added powershell and remote management tools to the FSW server.

I’m not sure what really fixed it, but it worked after installing powershell and remote management tools to the FSW server.

I could then manage the DAG and move or create a DAG with th FSW on the non-exchange server.

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Once this completed, I could then create copies of the databases.

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And the other Database

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And finally

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So let’s “switchover the Server”.

When an administrator makes a database copy the active mailbox database, this process is known as a switchover. When a failure affecting a database occurs and a new database becomes the active copy, this process is known as a failover. This process also refers to a server failure in which one or more servers bring online the databases previously online on the failed server. When either a switchover or failover occurs, other Exchange 2010 server roles become aware of the switchover almost immediately and will redirect client and messaging traffic to the new active database.

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Note the mounted databases on EX2010-2 switched from mounted to healthy.

This was a longer process than I expected, but its working finally.

Hope it helps                                                                     Home to atthedatacenter.com

dw                                            

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One Comment

Leave a Comment
  1. Christian Hoffmann / Dec 13 2010 7:18 am

    I had exactly the same problem and solved it without installing anything on the FSW server.
    What does the trick is deactivating the UAC on the witness-server and adding the “Exchange Trusted Subsystem” to the local Administrator group on the FSW-Server.

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