Rightsizing AWS OpenSearch. This was a recent task of mine that came up to help one of our engineering teams. The problem with rightsizing effectively is that it’s more of an art than a science because requirements are so vastly different. There isn’t a one-size-fits-all approach.
What I’ve learned is, try your best to get a good estimate, roll it out, then monitor the heck out of it. If monitoring proves something different, then adjust as needed. Amazon has recommended best practices documentation on sizing and monitoring.
Aside from the docs/links above, I also found these videos helpful: