3 Node DAG with DR site

Question

Hi team,
I have a primary site with 2 CAS (WNLB) and 2 MBX servers with DAG configured. I want to extend this to include a DR site with 1 CAS and 1 MBX server. FSW on Primary site is set to CAS server.
If the PRimary site goes down completely, is it correct that the DR DAG member will not come up since there's no majority?
related to Q1, what steps do i need to follow to get the DR DAG node up and running?
If I set up a secondary FSW on the DR Site CAS, can I get majority vote and get the DR DAG node up automatically?
What's DAC's role here?
Thank you.
Chris!

Answer 1

Hi Crypto,
1.If the PRimary site goes down completely, is it correct that the DR DAG member will not come up since there's no majority?For a 3 server DAG it will be offline if two servers
are lost.  You must manually intervene at this point. we discourage automatic fail-over of DAG to DR manual fail-over is better. Make sure DAG is in DAC mode.
2. related to Q1, what steps do i need to follow
to get the DR DAG node up and running?
Install a server with all roles and add the MBX server to the DAG install an ADC in DR site and point Exchange server in DR to the ADC in DR using Set-ADServerSettings. Configure alternate witness(FSW in a 3 member DAG check next question's answer). 
Please check this to configure alternatewitness server and enable DAC on the DAG. http://technet.microsoft.com/en-us/library/dd297934(v=exchg.150).aspx
3.If I set up a secondary FSW on the DR Site CAS, can I get majority
vote and get the DR DAG node up automatically?
In a 3 member DAG FSW is being ignored. Read this. You have to manually bring the DR Exchange online.
4.What's DAC's role here?
We enable DAC to prevent split-brain when data center goes offliine.
http://technet.microsoft.com/en-us/library/dd979790(v=exchg.150).aspx
Please read this http://social.technet.microsoft.com/wiki/contents/articles/23333.exchange-2013-dag-datacenter-failover-and-disaster-recovery.aspx
Please read this to understand the HA changes in CU1
http://blogs.technet.com/b/scottschnoll/archive/2013/04/02/high-availability-changes-in-exchange-server-2013-cumulative-update-1.aspx
Thanks, MAS
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Hi MAS,
Thank you and sorry for the delay. Can I have the same setup with 3 nodes under a single site and keep one node as a DR location (But not in an AD Site)?
Thank you,
Chris.