Mysterious drive capacity numbers....?

[Karl Auer]

On Tue, 2010-12-14 at 12:01 +0100, Loïc Grenié wrote:
> > Filesystem           1K-blocks      Used Available Use% Mounted on
> > /dev/sdb1            961432072  57820632 854773440   7% /media/nc1
> >
> > Note that the amount used is given as 57,820,632K - about 57GB.
> >
> > But 961 - 854 = 107. Where did the extra 50GB go?
> 
>     That's 5% reserved "for root". Any non-root user can put data on the
>   drive as long as used space is less than 912594072k. As soon as used
>   space goes above 912594072k, only root can write (up to 961432072k).

Makes sense, and as soon as I read your message I remembered about
reserved space. I realised after writing my previous message that any
formatting overhead is of course already reflected in the reported size
of the partition. Which does mean a pretty large formatting overhead,
but the 50GB I've "lost" are in addition to that.

dumpe2fs shows a "reserved block count" of 12209500 and a block size of
4096. That's pretty close to 50GB :-) I think I will use tune2fs to
lower that.

Running "df -k" as root does not show different numbers, which is mildly
irritating.

Thanks, K.

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Karl Auer (kauer at biplane.com.au)                   +61-2-64957160 (h)
http://www.biplane.com.au/kauer/                   +61-428-957160 (mob)

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