We've had Moodle since 2005, and I feel very confident with it. However, we've now come to a point where we need to free up some disk space and delete some old courses. First, I identified some of the largest courses by using the course sizes report, which I know isn't completely accurate because it says we have almost 1TB of course data, when I know the number is closer to 500GB, at least in moodledata (and the db is less than 30GB). That said, I went ahead and deleted about 75GB worth of courses according to that report, and it actually cost an additional 13GB of space in moodledata. I've looked for solutions to this problem, and found two posts referring to it clearing up after four days or several days, but I've waited a full week, and still don't see significant space freed up. Meanwhile, our Moodle site is still in use, and my free space is growing smaller everyday. (I also tried using Moosh on my dev system, as suggested in some posts, but the results were the same.) As I said, it's been a week since I deleted the courses, and I still have less space than I would have if I had not deleted the courses at all.
Any suggestions would be greatly appreciated.
Running Moodle 3.5.4 on Ubuntu 18.04 (separate database and web front end servers)