*BSD News Article 26061


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From: durham@w2xo.pgh.pa.us (Jim Durham)
Newsgroups: comp.os.386bsd.questions
Subject: Re: [FreeBSD] free diskspace?
Message-ID: <19@w2xo.pgh.pa.us>
Date: 9 Jan 94 00:51:06 GMT
References: <gate.8oaTFc1w165w@subway.hacktic.nl> <CJA41o.8I4@usenet.ucs.indiana.edu>
Organization: Jim's Basement
Lines: 52

In article <CJA41o.8I4@usenet.ucs.indiana.edu> pitts@mimosa.astro.indiana.edu (Jim Pitts) writes:
>In article <gate.8oaTFc1w165w@subway.hacktic.nl>,
>Koen Martens <gmc@subway.hacktic.nl> wrote:
>>
>>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%    /
>>/dev/wd0e       266030  142957   96470    60%    /usr
>>/dev/fd0a         2847    1928     919    68%    /mnt
>>
>>As you can see, for /dev/wd0a 13364+12108 does not equal 28303.. Also,

stuff deleted

>>reported a negative value for available disk-space! fsck however does
>>
>>Is this a known problemm? And if yes, could you please tell me what to
>>do to fix it??
>>


stuff deleted
>This is not a problem.  When you make a new BSD filesystem 10% of the total
>space is reserved as space that only 'root' can write to.  When you see

stuff deleted

>To answer your possible next question, this space is required by the BSD
>filesystem.  It is used to insure that problems like fragmentation are kept
>to a minumum.  I am sure that there are ways to make this space avaliable
>for general consumption, but I would not suggest doing it.  It makes for
>a -very- inefficent file system.  It is an integral part of the filesystem
>itself and is crucial to its proper operation.

What you need to do is type "man tunefs", which will give you
a discription of /etc/tunefs. tunefs can set many parameters
concerned with the disk system, among which is the one discribed
in your postings called "minfree". minfree is normally set at
10%, which, as above, is the space held back from normal users.

According to the man page, if you set it to 0, you will cut disk
throughput by a factor of up to 3, not a good idea.

I haven't played with this on FreeBSD, but I have set minfree down
to 5% on my Microvax, with minimal problems.

-Jim Durham