Whenever your server runs out of disk space: it’s good to know who steals your gigabytes. Formerly I used
du / | sort -n | tail -30 to get a quick impression.
Today, Andree pointed me to
gt5, a mighty tool based on ncurses. Its user interface is similar to those of htop or mc. It tells a lot of disk usage, so you will know very quickly where your space has gone.