What Admin / Monitoring Topics Do You Think Are the Most Important?

I’m prepping for writing specifically on “Configuration and Monitoring” in MongoDB. I have already covered things like auth, backups, replication, etc.

So, this is more about the general concept of the config file, monitoring tools, and troubleshooting issues.

I have a good idea of the things related to that I know I’d want to talk about, and things I have run into … but I’m curious what other people in the community think are import in these areas, or if they have any great tips?

For example, specific config parameters you think are important or some tricks you have for troubleshooting, monitoring, etc. (happy to credit anyone!)