Many of the good Systems Administrators and Database Administrators I know take notes. I have in the past myself. And I've used several (physical) notebooks to write my notes in. However, I didn't do nearly as well in finding the notes later. Certainly, the act of writing my notes down helped me to remember them, but if I couldn't fully remember the notes, it became another level of effort to find my notes in my notebook (or notebooks if I'd misplaced the original or if it was a completely different notebook for one reason or another).
For a while I used a personal Wiki tool (didiwiki) that I used on my local computer. (This is obviously a Linux workstation that I was using as there isn't an easy way to run this on Microsoft Windows(tm)). I was able to search through my notes, but I had no way to easily share it across from my work computer to my home computer and keep them consistent.
Soon after this, I found Zim. This is a desktop wiki and only runs locally. But it does have a built in "web server" that you can run on any port that people can connect to. This way I can easily "share" my notes (but mostly for myself). Zim became my main productivity tool for making notes.
Zim allows a limited amount of formatting, so this reduces this to a less distracting interface. I have bold and italic and underlined (and an unformatted style that is a monospaced font used for computer code), but I don't have a lot of fonts to select from. This allows me to concentrate more on what I'm writing and not be distracted by formatting. Another advantage, in my mind, is that I'm never waiting on Zim. Sometimes Windows applications, especially "large" programs like a Word Processor, just freeze up and needs to do things in the background. I've never seen this happen with Zim (but of course, that would also depend on the CPU and memory you have in your computer). But overall, Zim is very lightweight and works without a significant amount of computing resources.
One of the biggest advantages for using Zim is my ability to search across multiple notes. I could easily save my notes in a text file (or multiple text files) without any formatting. But I still wouldn't be able to easily search through a text document. I know some people will argue about that and say I have a FIND (or SEARCH) command in their note application. And that is true. And it may meet their needs. However, I can easily build different notes in Zim and link them together (via a Hyperlink or multiple hyperlinks). And now I can build an organizational structure for my notes and still search through them on some piece of code or some unique (or hopefully unique) word and find the note or notes I'm looking for. I've had to reorganize my links several times to get an optimum structure for my notes and finding the information in the future.
Earlier I mentioned that Zim has a limited number of formatting options. I mentioned the standard bold, italic, underscore (underlined), and preformatted (a mono-spaced font that works well with computer code or anytime you want to emphasize using a mono-spaced font). It also allows 7 heading styles. If you're familiar with HTML (Hyper Text Markup Language or web page layout) you'll recognize them as H1-H7. Really, I don't do much with these other than to break my notes up into different sections. I don't have to use more than levels 1-3 for the most part (and one of the add-ins for Zim allow you to put a Table of Contents on each page or in each note).
The last really powerful thing that Zim does for me, is to export my complete notebook directly to HTML pages. I frequently share my Notebooks at work with my co-workers so they have these as a reference. And because it's a static web page I copy over to a web server, they can't make any updates to my notes. I can also connect to my notes from someone else's computer at work if I need access to my notes as well. And the best part is that since it's static, I don't have to worry about people making updates (either accidentally or as a malicious act).
Maybe Zim will meet your needs and maybe it won't. But it solves a huge problem for me and I have multiple notebooks on a daily basis. One for my personal notes and one for specific things I do for my employer. I also have a friend who is a writer, and he's been using Zim to outline some of his books. So there is a lot of flexibility in this note taking tool.