disk usage monitor figures don't add up?

[Lai Zit Seng]

Actually this is math is "normal" to df.

The capacity number is correct, the used number is correct. But the 
available number is under-reported. It kind of makes you think your disk 
is full before it is really full. Note that even while non-root programs 
start to grapple with out-of-disk problems, programs running as root can 
still continue writing until the disk is truly full.

Regards,

.lzs


On Thu, 9 Dec 2004, Gene Heskett wrote:

> Greetings;
>
> I need a bit of help from the ext3 filesystem folks I think.   I'm
> haveing a comprehension problem here.  A snip from a df report:
>
> /dev/hdd3      176100712   165509176   26340  100.3% /amandatapes
>
>> From the above, there is about 10GB on the missing list!  Amanda just
> bailed out early because the disk was full, while the 2 figures on
> the left claimed there should have been somewhere between 10GB and
> 11GB of space left, not the 26 megs shown above.
>
> The output of a du . on that partition, before I ran the amflush, was
> 165509176 bytes total used out of 176100712 that df claimed it has
> for a total, both in 1024 byte kilobytes.
>
> So my question is: Where is the math broken?  Both du and df, or my
> head?
>
> Surely there cannot be 10+GB tied up in inodes and journals?