Like this ( i remember this has been mentioned already):

somehost:~ # mount | grep mysql
/dev/sda3 on /var/lib/mysql type ext3 (rw,acl,user_xattr)
somehost:~ # df -h /var/lib/mysql/
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda3             215G   75G  129G  37% /var/lib/mysql
[download]

Or a variation of it.

I read this: 37% (75G of 215G) of /var/lib/mysql are used".

Or i didn't understand the problem, who knows.

Karl