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Here I have a 2-node SQL Server 2016 AlwaysOn Availability Group cluster, with 1 primary and 1 secondary.

The question is - what is the optimal way to install Microsoft Updates on the servers in the cluster? I have struggled to find good, clear recommendations on this.

Here is my current thinking:

  1. Install updates using Microsoft Update on the secondary
  2. Restart the secondary to finish the updates
  3. Perform a manual failover from the Primary to the Secondary
  4. Install updates using Microsoft Update on the new-secondary (former primary)
  5. Restart the new-secondary (former primary)
  6. Perform a manual failover from the new-Primary to the Secondary, making the original primary the primary again

My understanding is that this will:

  • Cause absolutely no application downtime
  • Cause no syncing errors
  • Cause no data corruption
  • The cluster will not generate errors when half the nodes are updated and the other half are not

Is this correct? Is there a better way to do this?

Thanks in advance - any help is greatly appreciated.

A X
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  • There's a detailed procedure here: https://docs.microsoft.com/en-us/sql/database-engine/availability-groups/windows/upgrading-always-on-availability-group-replica-instances – Greg Askew Feb 20 '21 at 21:11
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    @GregAskew Isn't this for Upgrade (i.e. Major Version) not update (patches)? – A X Feb 20 '21 at 21:16

1 Answers1

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Here's a step-by-step guide on how to achieve what you want:

Apply SQL Server patches or cumulative updates in SQL Server Always On Availability Groups

You might scroll down right to the "Preparatory Phase" section skipping all the "water".

BaronSamedi1958
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