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Dealing with Exchange DAGs Backups?

Exchange DAG Passive Active Messages Message Level

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#1 opjose

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Posted 21 December 2016 - 01:06 PM

I have two virtual Exchange 2013 servers in a DAG configuration.


I am currently backing up both servers and have the active database server also performing the message level backups.


I had problems backing up the passive database server, until support pointed out that an INI file change was needed on the passive machine.. Ugh!


Now I can back up both servers, which raises a few questions...


Can I enable "Message Level" backups on both servers?


If so does the Barracuda Backup Appliance de-duplicate the messages between the two servers?




I switch the active server when I am performing software updates to avoid downtime.  Each time I do so I am forced to modify the INI files accordingly and delete and recreate the "sources" and schedules to get a reliable backup. Backups fail if I don't do these two things with "Connection Lost" errors that are not really applicable.


However doing so places the retained data out of sync so to speak, as the Barracuda appliance now thinks it is dealing with a different and new machine.  How can I avoid this?


I've been told by Tier 2 support that an upcoming firmware & agent update will fix this and remove the need for the configuration changes.

#2 James Scott

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Posted 21 December 2016 - 01:11 PM

Could you detail the change to the INI file support had you make on the passive Exchange server? We are having a very similar issue, and thus far the support technician has been baffled and unable to assist. Any help would be appreciated, thanks!



#3 opjose

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Posted 06 January 2017 - 12:18 AM



The above details the settings.


Strangely no one in support knew about this.


Everyone kept insisting that there was an issue with our network, latency, configuration, etc. etc. etc. 


One day someone at tier 2 said "oh" and referred me to the above link.


The changes did the trick, though remember that you will have to delete your "source" server then add it back, after restarting the service on the Exchange machine.


The INI change is only done on the passive database host.... which means that if you switch the active member you'll have to modify the INI again on each machine...


Support says this will change in a future update.

#4 opjose

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Posted 26 April 2017 - 04:15 PM

At the "Barracuda Campus" search for


"How to Back Up Microsoft Exchange Server 2010, 2013 and 2016 DAG Passive Database"


The Link above does not work properly...

#5 Fabian Roth

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Posted 19 July 2017 - 02:03 AM

There are actually two links in the "Barracuda Campus":

How to Back Up Microsoft Exchange Server 2010, 2013, and 2016 DAG: https://campus.barra...X2010DAGBackup/

How to Back Up Microsoft Exchange Server 2010, 2013, and 2016 DAG Passive Database: https://campus.barra...assiveDBBackup/

I also found an old article: How can I backup clustered Microsoft Exchange servers with the Barracuda Backup Service? https://campus.barra...ackup Service?/


How does the configuration have to be if there are passive DB's on all Exchange 2016 servers?

And how do I need to configure Barracuda Backup for MLB with Exchange 2016 DAG's on all servers?

#6 Shawn Lubahn

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Posted 03 August 2017 - 09:56 AM

Hi Fabian,


The simple explanation to backing up an Exchange DAG is to install the Barracuda Backup Agent on each server/node and add them as a source to the Backup > Sources page. By default, this will backup every active Exchange database that lives on each server/node. If a database moves from one node to another, it will be backed up on the new node.


Backing up the passive databases, essentially the non-active copy of the active databases located on another node, is not configured by default, and is not required/necessary. This is more of an optional backup that can be configured, but you would essentially be backing up each Exchange database twice using this method.


Configuring message-level backup is done on the Client Access Server (CAS). This is a separate backup from the agent/database backups.






#7 opjose

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Posted 02 November 2017 - 05:08 PM

Sources page. By default, this will backup every active Exchange database that lives on each server/node. If a database moves from one node to another, it will be backed up on the new node.



This is exactly what DID NOT happen.


The default is to back up databases on both servers BUT the server with the passive copy fails unless the .INI changes are made to it.


This in turn requires always editing the passive server so backups run successfully.


Note: I have not compared the results on newer Barracuda agents. At the time I was told this would be fixed in the future and I have not gone back to see if it has.