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

SQL Server Migration Assistant
SQL Server Migration Assistant
A Microsoft tool designed to automate database migration to SQL Server from Access, DB2, MySQL, Oracle, and SAP ASE.
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  1. Sean Gallardy - MSFT 1,901 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 14,006 Reputation points Microsoft External Staff
    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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