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Adding a 3rd Exchange 2013 Server to DAG RRS feed

  • Question

  • 2012 Server R2 Standard
    Exchange 2013 Version 15.0  (Build 1178.4)


    Hi Experts,

    I Have a Exchange 2013 DAG which consists of 2 Exchange 2013 (Active and Passive on Windows 2012 R2 Standard) 
    and 1 FileShare Witness. All 3 are virtual machines running on XenServer 6.1 which runs out of life in March 2019.

    I'm looking at migrating these VM's off Xenserver and onto VMware but the process of doing this requires 
    registry removal of all XenServer keys and drivers which I'm uncomfortable doing in case something goes 
    wrong then I'm unable to go back. 

    I'm looking at creating another Exchange 2013 server on VMware ESXi 6.0, and adding it to the DAG.
    The idea is to replace the current Passive Exchange 2013 server with this newly created one.

    My questions are:

    1. Will adding another Exchange 2013 server cause the Cluster Quorum to be unbalanced because of the even number of servers being used?

    2. Will I need to change the cluster quorum mode from "Node and File Share Majority" to "Node Majority"? If so how will I do this?

    3. Seeing that the idea is to replace the current passive exchange 2013 with the new one, will I still need to change the cluster quorum mode? Assuming I do, can I change it back to "Node and File Share Majority" after taking the current passive server offline? 


    Kind Regards
    GMSS

    Wednesday, November 21, 2018 11:16 AM

Answers

  • 2012 Server R2 Standard
    Exchange 2013 Version 15.0  (Build 1178.4)


    Hi Experts,

    I Have a Exchange 2013 DAG which consists of 2 Exchange 2013 (Active and Passive on Windows 2012 R2 Standard) 
    and 1 FileShare Witness. All 3 are virtual machines running on XenServer 6.1 which runs out of life in March 2019.

    I'm looking at migrating these VM's off Xenserver and onto VMware but the process of doing this requires 
    registry removal of all XenServer keys and drivers which I'm uncomfortable doing in case something goes 
    wrong then I'm unable to go back. 

    I'm looking at creating another Exchange 2013 server on VMware ESXi 6.0, and adding it to the DAG.
    The idea is to replace the current Passive Exchange 2013 server with this newly created one.

    My questions are:

    1. Will adding another Exchange 2013 server cause the Cluster Quorum to be unbalanced because of the even number of servers being used?

    2. Will I need to change the cluster quorum mode from "Node and File Share Majority" to "Node Majority"? If so how will I do this?

    3. Seeing that the idea is to replace the current passive exchange 2013 with the new one, will I still need to change the cluster quorum mode? Assuming I do, can I change it back to "Node and File Share Majority" after taking the current passive server offline? 


    Kind Regards
    GMSS

    1. No, it will simply switch to node majority. Meaning it will not use the File Share Witness as a tie breaker. Instead, you will need 2 of 3 nodes to be active to maintain quorum in the event of a immediate failure of a node.  Note: in 2012 there is also support for dynamic quorum: https://blogs.technet.microsoft.com/askcore/2016/03/21/behavior-of-dynamic-witness-on-windows-server-2012-r2-failover-clustering-3/. But dont design the DAG based on that. Just know that with 3 node in a DAG, you need to keep 2 up to maintain quorum and keep the databases mounted.

    2. Exchange will handle that automatically for you. You wont need to do anything. The quorum model will change w/o any other work from you other than simply adding the additional mailbox server to the DAG.

    3. There is not really a concept of an active and passive server in a DAG. They are really peers. If you remove a mailbox server from the DAG in the future it will go back to the Mode and File Share Majority model automatically using the defined File Share Witness you are using now. Taking the server "offline" is not enough. It has to be removed from the DAG.


    Wednesday, November 21, 2018 11:57 AM

All replies

  • 2012 Server R2 Standard
    Exchange 2013 Version 15.0  (Build 1178.4)


    Hi Experts,

    I Have a Exchange 2013 DAG which consists of 2 Exchange 2013 (Active and Passive on Windows 2012 R2 Standard) 
    and 1 FileShare Witness. All 3 are virtual machines running on XenServer 6.1 which runs out of life in March 2019.

    I'm looking at migrating these VM's off Xenserver and onto VMware but the process of doing this requires 
    registry removal of all XenServer keys and drivers which I'm uncomfortable doing in case something goes 
    wrong then I'm unable to go back. 

    I'm looking at creating another Exchange 2013 server on VMware ESXi 6.0, and adding it to the DAG.
    The idea is to replace the current Passive Exchange 2013 server with this newly created one.

    My questions are:

    1. Will adding another Exchange 2013 server cause the Cluster Quorum to be unbalanced because of the even number of servers being used?

    2. Will I need to change the cluster quorum mode from "Node and File Share Majority" to "Node Majority"? If so how will I do this?

    3. Seeing that the idea is to replace the current passive exchange 2013 with the new one, will I still need to change the cluster quorum mode? Assuming I do, can I change it back to "Node and File Share Majority" after taking the current passive server offline? 


    Kind Regards
    GMSS

    1. No, it will simply switch to node majority. Meaning it will not use the File Share Witness as a tie breaker. Instead, you will need 2 of 3 nodes to be active to maintain quorum in the event of a immediate failure of a node.  Note: in 2012 there is also support for dynamic quorum: https://blogs.technet.microsoft.com/askcore/2016/03/21/behavior-of-dynamic-witness-on-windows-server-2012-r2-failover-clustering-3/. But dont design the DAG based on that. Just know that with 3 node in a DAG, you need to keep 2 up to maintain quorum and keep the databases mounted.

    2. Exchange will handle that automatically for you. You wont need to do anything. The quorum model will change w/o any other work from you other than simply adding the additional mailbox server to the DAG.

    3. There is not really a concept of an active and passive server in a DAG. They are really peers. If you remove a mailbox server from the DAG in the future it will go back to the Mode and File Share Majority model automatically using the defined File Share Witness you are using now. Taking the server "offline" is not enough. It has to be removed from the DAG.


    Wednesday, November 21, 2018 11:57 AM
  • Hi Andy,

    Many Thanks for you response and do appreciate your answers.

    Kind Regards

    Keith

    Thursday, November 22, 2018 1:40 PM