Sometimes it comes handy to have some commands that help you find big files, like it happened to me at work, the server was full, control mysql was down due to that, imagine almos 50 websites not working..
Search for bigger files on all subdirectories
du -hsx * | sort -rh | head -10
this one is another command that does something similar, but on all disk
du --max-depth=7 /* | sort -n
du --max-depth=7 /* -h | sort -n
To have a human readable size value.