> making df, indicate that my /usr partition is full, making a du -s and
> making the sum by hand indicates that 250MB are free, making a du -s .
> indicates that in fact the disc is full. Now i have in /usr only directories
> so the sum of the directories should equal the disk usage or am i wrong?
> and other fact: even if i remove things, the df reports that the free
> space remains 0Bytes.....
Have you figured in the reserved blocks count? The ext2 filesystem, by
default, reserves a certain amount of space exclusively for the root user,
so that when some mere mortal fills up all the disk space, system daemons
and the like don't come crashing to a * halt for lack of room.
You can change the amount reserved for each partition; see "man tune2fs".
It's probably not a good idea to push this too low on the partition where
the root directory ("/") is, but other partitions probably won't need
nearly as much as the default (5%, IIRC).
Also remember that files are stored in finite blocks, and just adding file-
sizes won't take end-of-file lossage into account.
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