Mixing SQL Versions on Production servers

We have a production 2019 SQL Server that has a few instances. We have a few upgrades coming up and we are considering adding some SQL 2022 instances onto this server.

  • What are the disadvantages of mixing versions on the same production server? * Would you do it?
    Thanks for your perspectives.

The disadvantages are the same as having multiple instances - resource usage. Each instance will need memory and will utilize all of the CPUs that are available - and if they are using the same storage then possible IO issues.

Can you do it? Yes
Would I do it? Depends...


Thank you, jeffw8713. Also I think another disadvantage is the likelihood of needing more frequent reboots due to one version needing a patch. I already have several SQL servers that are waiting on a restart..... And there is the issue of having to get approvals for each application related to the instance when the server needs a reboot.
I would like to hear from others.

If you are applying the monthly security patches - which you should be doing anyways, then patching the SQL Server instances can be scheduled at the same time and there would not be any issues with getting approvals for the scheduled patch restart.

If you are not applying the monthly security patches - why not?