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Additional Exchange Server for DR site RRS feed

  • Question

  • Hi all,

    We are planning to deploy additional exchanhe server that will be located on our DR site.currently, we have 2 exchange server and 1 file witness server in our main site.do i need to build an alternate file witness also on DR site for data center switchover? Or its possible to do data center switchover without alternate witness server? Is DAC also recommended to be enabled? Thanks!

    Monday, April 15, 2019 12:18 AM

Answers

  • Hi

    Yes. You can preconfigure alternate witness server and  there is no issue.

    But when you will use Restore-DatabaseAvailabilityGroup command that is the scenario alternate witness server will use.


    Thanks & Regards, Kumar N

    • Proposed as answer by Niko.ChengModerator Tuesday, April 16, 2019 9:13 AM
    • Marked as answer by danpaolo Monday, April 22, 2019 12:44 AM
    Tuesday, April 16, 2019 4:34 AM

All replies

  • Hi Danpaolo,

    do i need to build an alternate file witness also on DR site for datacenter switchover?

    --Yes, The Alternate Witness Server is used to store file share witness data. It is used only as part of a datacenter switchover process. If the DAG is extended across multiple datacenters in a site resilience configuration, we recommend preconfiguring the alternate witness server and directory. 

     Is DAC also recommended to be enabled? 

    --Yes, DAC mode should be enabled for all DAGs with two or more members that use continuous replication, it is used to control the database mount on startup behavior of a DAG, this control is designed to prevent split brain from occurring at the database level during a datacenter switchback. Details see: Datacenter Activation Coordination mode.


    Best Regards,
    Niko Cheng


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    Monday, April 15, 2019 7:00 AM
    Moderator
  • Hi,

    Already having two exchange server's with file share witness in primary site.

    If you planning to install another exchange server in DR site, not required File share witness server due to odd numbers (3 Exchange servers) in the DAG and quorum type will adjust as Node Majority.

    Multi site DAG environment should be enabled DAC mode to avoid split brain situations.

    From Windows 2012 onwards, Dynamic quorum introduced in cluster level so if you shutdown exchange server with order and time interval - it will work one exchange server (DR) using dynamic weight with concept of  last man standing out. So this scenario not required alternate witness server.

    if unplanned outages on production environment, You should restore the DAG using  Restore-DatabaseAvailabilityGroup command with alternate witness server.

    FYR,

    Restore-DatabaseAvailabilityGroup -Identity DAG1 -ActiveDirectorySite Redmond -AlternateWitnessServer CAS4 -AlternateWitnessDirectory D:\DAG1


    Thanks & Regards, Kumar N

    Monday, April 15, 2019 7:16 AM
  • Hi,

    Already having two exchange server's with file share witness in primary site.

    If you planning to install another exchange server in DR site, not required File share witness server due to odd numbers (3 Exchange servers) in the DAG and quorum type will adjust as Node Majority.

    Multi site DAG environment should be enabled DAC mode to avoid split brain situations.

    From Windows 2012 onwards, Dynamic quorum introduced in cluster level so if you shutdown exchange server with order and time interval - it will work one exchange server (DR) using dynamic weight with concept of  last man standing out. So this scenario not required alternate witness server.

    if unplanned outages on production environment, You should restore the DAG using  Restore-DatabaseAvailabilityGroup command with alternate witness server.

    FYR,

    Restore-DatabaseAvailabilityGroup -Identity DAG1 -ActiveDirectorySite Redmond -AlternateWitnessServer CAS4 -AlternateWitnessDirectory D:\DAG1


    Thanks & Regards, Kumar N

    Hi Kumar,

    I was a bit confused.we were not planning to make a file witness server on dr site.i was planning ayo preconfigure alternate witness server.

    Tuesday, April 16, 2019 12:57 AM
  • Hi

    Yes. You can preconfigure alternate witness server and  there is no issue.

    But when you will use Restore-DatabaseAvailabilityGroup command that is the scenario alternate witness server will use.


    Thanks & Regards, Kumar N

    • Proposed as answer by Niko.ChengModerator Tuesday, April 16, 2019 9:13 AM
    • Marked as answer by danpaolo Monday, April 22, 2019 12:44 AM
    Tuesday, April 16, 2019 4:34 AM