We are attempting our first ever side by side upgrade of a 2 node(multi-subnet, enterprise edition) AG from sql 2016 to 2019. I have some questions on how best to approach this:
- Do we create a brand new cluster and AG with sql2019 and use log shipping to populate and cut over to the new environment?
- Do we add 2 new 2019 nodes(1 in each existing subnet), and set them up as secondaries in the existing AG? I know normally you can't mix versions in an AG, but for an upgrade like this I've read it's done without issues as long as you don't try to fail back over to the older version nodes.
- How are AG listeners handled in #2? I think we should be able to use the existing listeners since the new nodes are in the same subnets as the old version of SQl nodes?
I can't find any step by step guides for this online when we are dealing with clusters and AG's