Upgrade a SQL Server failover cluster from SQL Server 2017 to SQL Server 2019 and applying a Cumulative update simultaneously

Question

Hi All,

Current:

• Microsoft SQL Server 2017 (RTM-CU20) (KB4541283) - 14.0.3294.2 (X64) Mar 13 2020 14:53:45 Copyright (C) 2017 Microsoft Corporation Enterprise Edition: Core-based Licensing (64-bit) on Windows Server 2016 Standard 10.0 <X64> (Build 14393: ) (Hypervisor)

We are planning on upgrading a 2 node SQL Server Failover Cluster to SQL Server 2019. We would like to minimize the downtime to a single reboot. Our plan is as follows:

1. Upgrade the Passive HOST1 from 2017 to 2019
2. Apply Cumulative Update 18 to HOST1
3. Initiate Upgrade on Active HOST2 -- midway thru, setup will cause automatic failover to Passive HOST1 -- database upgrade will occur. HOST1 becomes Active. HOST2 becomes passive
4. Complete upgrade on HOST2
5. Apply Cumulative Update 18 to HOST2.

Question: can I apply the Cumulative Update (Step 2), before initiating the upgrade on the Active host (Step 3) ??? A yes answer means we only go through one reboot.

Thanks for any help you can provide.

--Dan

Answer 1

Hi @DJAdan

your process looks good, i would recommend two things.

complete Step 1 and 2 on Host1, then reboot that node - finished
Step 3 - manually failover your instance via Failover Cluster Manager... it will move your resources and upgrades the databases
then complete Step 4 and 5 on Host2, reboot and done.

Do NOT rely on the upgrade process to move your resources... do it on your own.
And you have to apply the CU before moving the resources on Host1!

Answer 2

Hi Bjoern,

Thanks for getting back to me.

A reboot of Host1 is a good idea.

The documentation does not suggest a manual failover. Why is this your recommendation?

Also, I don't understand your comment "And you have to apply the CU before moving the resources on Host1!" I thought I had already done that in Step 2?

Thanks again,

--Dan

Answer 3

Thanks Bjoern,

Paranoia is a good thing in our business! We can't afford downtime and I don't want to screw it up.

Failover Cluster Manager is a simple way to perform a controlled failover, and I'm surprised the Upgrade documentation doesn't suggest it as a preferred option. Especially if there is a concern that setup might leave you stuck somewhere in the process !!

--Dan

Answer 4

Thanks Bjoern!