Specifically, a wiki which uses a non-database backend. I like Dokuwiki for this, but anything which basically saves in text files is fine.

(Why? Because you don’t need to bring up the database and/or fix the web server to grep for the page you need right now.) …

Every document should start with “here’s what you need to know at 0200”, continue with “here are our typical uses” and finish with “this is the history of this tool here”.

Whenever possible, quote exact error messages (so they are greppable!) and write responses to them. If you are recommending a course of action, write it in commands that are easy to cut and paste – one per line.

Then make sure you have an automatically sync’d copy of it at every major location.

Any time someone discovers that it’s out of date, that needs to go in your ticket system and be addressed the day after the incident. It does not need to be the responsibility of the person discovering the discrepancy. Don’t make people do extra work when they find mistakes, they will gloss over them.

This is also where general culture facts go – conventions on IP addresses, names, vendor contacts, how you build racks, checklists for new employees and suspension of ex-employees, etc.