Upgrading a SQL failover cluster - OS and SQL versions

Algon 1 Reputation point
2021-03-03T16:01:51.733+00:00

Hi

I need to upgrade a 2 node SQL failover cluster currently running Windows 2016 Std and SQL 2016 Std to Windows 2019 and SQL 2019 Std.

I understand I can do a rolling upgrade by essentially upgrading the passive node first then failing over to it.
However, I'm wondering if it's cleaner and possible to just add a new node to the cluster with the newer OS version and SQL version then just failover to this instead doing an upgrade?

Cheers

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  1. Sean Gallardy - MSFT 1,876 Reputation points Microsoft Employee
    2021-03-03T20:45:39.167+00:00

    However, I'm wondering if it's cleaner and possible to just add a new node to the cluster with the newer OS version and SQL version then just failover to this instead doing an upgrade?

    Yes, you can do this as well. Rotate a node in, take a node out, or however you'd like. Once you fail over to SQL 2019, though, the databases will be upgraded and there is no going back to 2016.

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  2. Algon 1 Reputation point
    2021-03-05T13:59:38.76+00:00

    HI Sean

    Thanks for your help on this. okay, that sounds great.
    Is it possible to add a third node to the cluster with the new OS and new SQL version instead of removing the existing passive node first or is SQL Std Edt still limited to 2 nodes in a cluster?
    Lastly, when I failover, will the databases retain their compatibility level of the version of SQL that they came from, i.e. if they are running at a 2016 compatibility level will this be retained after I failover?

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  3. AmeliaGu-MSFT 13,906 Reputation points Microsoft Vendor
    2021-03-08T02:31:15.667+00:00

    Hi Algon-2141,

    Is it possible to add a third node to the cluster with the new OS and new SQL version instead of removing the existing passive node first or is SQL Std Edt still limited to 2 nodes in a cluster?

    On the Windows server Standard edition, SQL Server Standard Edition failover cluster can only support 2 nodes per instance.
    I’m afraid you have to perform a rolling upgrade to upgrade SQL Server failover cluster.
    Please refer to RDBMS high availability and Upgrade a failover cluster instance which might help.

    Best Regards,
    Amelia

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