That will be a really quick and short blog post. I would like to share with you a graph which I made when I was checking which services/roles connect to SQL Server and which databases are utilized by particular items.
Click the image if you want to open it in an original/bigger size.
I hope that it will be helpful for you because I believe that one image is worth thousands of words.
Here you have got also mindomo’s file which you can import and edit on www.mindomo.com (works perfectly with google drive): Sitecore 9.1 XP Scaled.mom