Moving from multi-subnet to single subnet


  • We're planning on implementing a 4 node WSFC across two DCs to support avaialbility groups. Both DCs will host a primary replica and a secondary replica for HA. Both DC will also provide DR for the other DC by hosting a asynchronous replica ( layout below).

    While it will initially be a multi-subnet WSFC my understanding is that they plan to implemnt a single subnet between the 2 DCs at a later date.    Assuming that there have to be IP changes at DC2 to accommodate the single subnet I'd appreciate any high level advice as to what type of impact this would have on the AG setup

    • Would we need to remove the DC2 nodes from the cluster or just change the networking addresses?
    • Would we need to recreate all or part of the AG configuration or would it be less drastic  (remove Listeners).
    • Any other thoughts


    DC1 - Node 1

    • Primary AG1

    DC1 - Node 2

    • Secondary AG1 (synchronous for HA - Primary is on DC1-Node1)
    • Secondary AG2 (asynchronous for DR - Primary on DC2-Node3)

    DC2 - Node 3

    • Primary AG2

    DC2 - Node 4

    • Secondary AG2 (Synchronous for HA - Primary is on DC2-Node3)
    • Secondary AG1 (asynchronous for DR - Primary on DC1-Node1)
    Sunday, September 29, 2013 6:05 PM


All replies

  • You just need to remove the virtual IP address that you won't be needing - both on the listener name and the WSFC. No need to remove the cluster nodes and add them back. Just make sure you work with your DNS administrators to properly clean up stale DNS records that point to the virtual IP address that you will remove

    Edwin Sarmiento SQL Server MVP Edwin Sarmiento SQL Server MVP
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    SQL Server High Availability and Disaster Recover Deep Dive Course

    Monday, September 30, 2013 4:34 PM
  • Hi peterfeakins,

    I just did a same migration days ago.

    • We don't need to move the nodes out, and then join them again. Just change the IP Address. But, please note, the Virtual IP Address(es) for the cluster must be update, it must be in the same subnet(s) of the nodes.
    • We don't need to recreate all AG configrations. We need to update the listeners' IP addresses.

    Jinchun Chen

    Jinchun Chen(JC)
    TechNet Community Support

    Tuesday, October 01, 2013 6:01 AM
  • Thank you for your replies.  Very helpful.
    Thursday, October 03, 2013 2:20 PM