*BSD News Article 25707


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From: terry@cs.weber.edu (A Wizard of Earth C)
Newsgroups: comp.os.386bsd.questions
Subject: Re: [FreeBSD] free diskspace?
Date: 7 Jan 1994 21:39:51 GMT
Organization: Weber State University, Ogden, UT
Lines: 30
Message-ID: <2gkkr7$ir5@u.cc.utah.edu>
References: <gate.8oaTFc1w165w@subway.hacktic.nl>
NNTP-Posting-Host: cs.weber.edu

In article <gate.8oaTFc1w165w@subway.hacktic.nl> gmc@subway.hacktic.nl (Koen Martens) writes:
>
>I am having a little trouble with my diskspace. When I do an 'df', it
>gives me something like this:
>
>Filesystem  512-blocks    Used   Avail Capacity  Mounted on
>/dev/wd0a        28303   13364   12108    52%    /

[ ... complaint the Used+Avail != 512-blocks ... ]

You are neglecting the effects of fragmentation and the default 10%
reserve that is not allowed to be used except as root.

The amount used and the amount available are correct after adjustment;
the total is without any adjustment.

There was some discussion a while back about reducing reserve based on the
disk size being pretty large; I never saw a number less than 4% bandied
about.  Look at the tuning (tunefs) and FS build (newfs) commands to
see what you can do about it.  In general, defragging will require a
smaller block size (I think the default is 8k).  Performance will be
reduced similarly if you reduce the block size (iozone drops 230% in
a reduction from 8k to 4k on my box).


					Terry Lambert
					terry@cs.weber.edu
---
Any opinions in this posting are my own and not those of my present
or previous employers.