Sysadmin

One thing that worked for me in a similar situation was to enforce an "owner" tag or some kind of registry on everything.

Basically, if you set something up, change some configuration, whatever - put your email address on it.

Write a readme.md or wiki or guide too, but at the very minimum put your name down as the owner so that when someone comes along and wants to know if it's safe to change/upgrade/delete, they can find you and ask. If someone leaves, you can do a quick search and get them to handover/write up anything they were responsible for.

Personally, I think the biggest challenge with documentation is keeping it up to date.

The only way I've found to be actually up-to-date on docs is to do GitOps and have self-documenting code. That way every change being made is automatically documented with a commit message.

If you can't do that because your tools aren't GitOps compatible, you need management to enforce some kind of documentation rule. Like every time a system gets touched, documentation needs to be updated. A project isn't complete until docs are done/updated.

This is easily said, but in practice it's just not going to happen. You need a team that both actually wants to this, and has the time to do it.

Many things will have a description or notes field — such as AD accounts, Exchange rules, SharePoint sites, and the like. Sometimes it’s visible to the user, and sometimes not. Always try to write something in there. That’s a great start.

I'm partial to infrastructure as code techniques as a way of writing things down and tracking changes, but that's obviously not always possible in corporate IT with "edge computing".

If you're documenting something related to code or a specific computer, I think readme .md files are the best, because you can't lose them.

If you're writing pure documentation, there are really nice markdown site generators like docusaurus, but if you're just making internal documentation, you can just file everything with an online cloud documentation tool like Notion or even Google Docs. If you want online documents like Google docs, but you don't want Google to have all your secrets, you can run your own corporate Nextcloud server, which is very common in Europe.

With things like Exchange rules, I wonder if people thought they were self-documenting? Like, our puppet manifests don't have separate documentation for them. For other things, we use a wiki for everything, and it is mixed success. People who know have to think it's something that someone else would need info about it to then write that info down. We often try and separate out "this is the high level goal" from the minutiae of doing it. And this could be a big problem if lots of people leave.

We use internal wiki, it works reasonably well. The problem is keeping the information updated

Honestly, anything is better than nothing. Write whatever you think is relevant and eventually you'll get a feel for formats that work for your company.