Debian 7 + MySQL 5.5 to Debian 9/10 + MySQL 8

Just looking for high-level feedback to make sure I’m starting in the right direction. We currently have a multi-site cluster running Deb 7 with Percona 5.5. Our plan is to upgrade to Deb 9 (possibly 10) and it would seem to make the most sense to go to Percona 8

In my mind, my simple solution is to simply build new Deb 9 + Percona 8 nodes and join them to the cluster. Let SST do it’s magic and then remove the old nodes from the cluster. Old DB nodes: “server1”, “server2”, “server3” and new DB nodes: “server4”, “server5”, “server6”.

Sounds easy… Might it actually work?

I’d probably want to rename the Deb 9 + Percona 8 servers to “server1”, “server2”, “server3”.

Hi Marco.Shaw

This won’t work for replication. I have been looking for some blog posts that will help you to piece together a strategy.

First of all, you should test your application queries. The optimizer changes substantially between major version upgrades and you can anticipate some big differences. You can use pt-upgrade from Percona Toolkit to help with that.

pt-query-digest could also pay dividends here.

This old post gives an outline of the kind of things you need to consider and covers replication in some part.
And this may be a useful read too

You’ll need a back out (back up) strategy too, in case of a failed upgrade. If those don’t help clarify, don’t hesitate to come back and I’ll see if I can get further insight for you.