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pazzoide76 avatar image
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pazzoide76 asked KaelYao-MSFT commented

Switch to the DAG from a single 2016 exchange server

Hi has everyone,
I have a question about the dag.
Currently one of my customers has a single exchange server 2016 with a single db inside which there are 300 mailboxes.
Now he would like to switch, adding another exchange server 2016, to a configuration with the DAG to ensure redundancy for the mailboxes.
For the transport part two load balancers will be placed in HA.
My question is:
Can I add the second exchange server, create the DAG, and replicate the existing db that contains the 300 mailboxes without creating disruptions?

Thank you

Greetings

office-exchange-server-administration
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Hi @pazzoide76

Just in addition, since you are going to deploy a two-node DAG, a witness server is required to maintain the quorum.
It can be any computer running Windows Server.
And there is no requirement that the version of the Windows Server operating system of the witness server matches the operating system used by the DAG members.


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1 Answer

AndyDavid avatar image
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AndyDavid answered pazzoide76 commented

Yes you can. In fact, that is really how any DAG is built.
Just ensure the new server matches the O/S and Exchange version and CU.

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Thanks for your answer.
I will be using windows 2016 at the same patch level and the same cu as exchange 2016.
So the creation of the dag and then the replication of the existing db will not cause any disservice, correct?

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Correct. When you add a mailbox server to a DAG, it doesnt affect the existing users. The databases are replicated to the new server, so no one will notice.

Note however:
When you bring up a new Exchange Server , it will be available for clients and Outlook will try to use it. This is expected and by design.
When you install the next Exchange Server, I would bring it up off hours and get a valid certificate on it, otherwise Outlook clients may get cert errors.

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Thanks for your answer.
You write:
When you bring up a new Exchange Server , it will be available for clients and Outlook will try to use it. This is expected and by design.
When you install the next Exchange Server, I would bring it up off hours and get a valid certificate on it, otherwise Outlook clients may get cert errors.
If before installing the new exchange I configure the load balancer to point only to the existing server (for all the various virtual directories autodiscover, mapi, owa etc) would I have the same problem?
Then once installed and loaded the ssl certificate I would add the second server in the load balancer.

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Internal - domain-joined clients will still find it it the SCP via autodiscover.

TOnce you bring up the new server, set the Autodiscover SCP and other client URLS to the load balancer FQDN and then it will be fine

https://docs.microsoft.com/en-us/powershell/module/exchange/set-clientaccessservice?view=exchange-ps

 Set-ClientAccessService -Identity "NewServer" -AutoDiscoverServiceInternalUri "https://LoadBalancedFQDN.contoso.com/autodiscover/autodiscover.xml" 



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let me know if you have any additional questions, otherwise, if you could, please an accept an answer so this can be closed.

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