I'm using ubuntu 12.04, and a warning always comes up saying I only have very little disk space left. I used bleach bit, tweak, some commands throught the terminal, but nothing works.

When I put the commant df -h, it'll give:

/dev/sda2 26G 11G 16G 41% /host

When I use disk usage analyzer it says 10.5 GB are used under disks. Then 1.9 GB under usr.