Patching SQL Servers in a cluster with WFC admin tool question

  • I've inherited a cluster and looks like this for simple terms; Im confused on which server is truly the active one, vs the passive one

    1. Core Cluster Resources are on Server A
    2. Active Role for Availability Group is Server B, passive role is on Server A

    I now need to patch both servers with OS updates.

    1. What server do I patch first and reboot ?
    2. Do I fail over the Core Cluster Resources to Server B, when it's time to reboot ?
    3. Is it ok to have core cluster resources and active role for AG's on different servers, or should I have both on the same server.

     

  • Thanks for posting your issue and hopefully someone will answer soon.

    This is an automated bump to increase visibility of your question.

  • I may not be able to provide a full answer as I've only worked with Availability Groups on 2016. However some more details on your setup might help people assist you. Are you able to post a screenshot of the cluster manager showing the resources? You can blank out any sensitive details.

    In particular I'm confused as to how the core resources are on one host and the availability group is on the other. I'm not suggesting you are incorrect, only that I'm not sure.

    I think there is a Microsoft guide to patching availability groups somewhere. I can't find it at the moment, I'll post it if I find it.

     

  • I never found my answer of which server is actually the active one, but I was able to patch by doing this;

    Manually fail over the active role on Server B to Server A...so now I had the core cluster resources and role on Server A, making sure that is the active server

    Patched and rebooted Server B

    Manually failed over role and core cluster resources, from Server A to B

    Patched and rebooted Server A

    Manually failed over role and core cluster resources, from Server B to A, making Server A be my consistent active server

    Hope that helps someone else

     

  • Thanks for the reply. I'm not sure what you mean by core cluster resources but I used the same pattern as you when I was patching the servers (manual failover, patch the inactive host, manual failover and patch the other host).

    I think the Microsoft guidance is to use SQL/SSMS to do the failover and not the Windows Cluster Tool but I can't find the reference for that. I think it also says that you should not use the Windows Cluster Update system as it does not understand SQL transaction and log records so could cause data loss when it starts a failover. Sorry, I can't find the reference at the moment. I always used SSMS to do the failover and never had an issue.

  • Attached is what I mean by Core Cluster Resources, highlighted in yellow...you do this in Failover Cluster Manager.

    My problem was that host (Core Cluster Resources) was on Server A, but active role for Availability group was on server B...so I didn't know which was the true active server, or maybe both of them were ??...I don't know.

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  • Thanks. I hadn't seen that option before. I did some research and I think the core cluster resources are the resources required to run the Windows cluster and they are managed separately to the availability group cluster. You can have them on the same or different hosts as you prefer. If the cluster resources are active on a host that you shut down they will move to another host automatically.

    I haven't quoted a source as I haven't found one that I'm sure is correct.

  • Cool, thanks for the follow up.

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