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Date:      Wed, 10 Jan 2007 13:08:59 +0100 (CET)
From:      Oliver Fromme <olli@lurza.secnetix.de>
To:        freebsd-stable@FreeBSD.ORG, ghelmer@palisadesys.com, koitsu@FreeBSD.ORG
Subject:   Re: 6.x loosing record of free space after filesystem fills?
Message-ID:  <200701101208.l0AC8xUV090061@lurza.secnetix.de>
In-Reply-To: <20070109195124.GA72863@icarus.home.lan>

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Jeremy Chadwick wrote:
 > Oliver Fromme wrote:
 > > Guy Helmer wrote:
 > > > I think we've finally found the cause of the problem - it wasn't just 
 > > > occurring after heavy use, but was visible right after filesystem 
 > > > creation!  We regularly built new filesystems with "newfs -U -O 1 -b 
 > > > 65536 -f 8192"
 > > 
 > > Why are you using those blocksize and fragsize settings?
 > > (If you store large files, then you should at least also
 > > decrease the inode density, using the -i option.)
 > 
 > Hmm... that begs the question: how do newfs -i and tunefs -f
 > associate with one another?

Not at all.  newfs -i specifies the inode density of the
new file system, and it cannot be changed later on with
tunefs.  (There are file systems that allocate inodes
dynamically, but our UFS isn't one of them.)  So this
puts a hard limit on the number of files that can be
stored on the file system.

The tunefs -f option (equivalent to newfs -g) can be used
to optimizes the way file data blocks are distributed
across cylinder groups.  The purpose is to minimize frag-
mentation and seek times.  It does not change the number
of inodes at all.

 > Shouldn't we document this somewhere?  Some places I can think
 > of, off the top of my head:

I think the most important settings (-i, -b, -f) are
already sufficiently documented in the tuning(7) manpage.

A link to tuning(7) should probably be included in the
newfs(8) and tunefs(8) manpages.  I haven't examined
what the Handbook says about all of this, but I don't
think that it makes sense to duplicate the manpage to
the handbook.  Instead, it would be helpful to include
a pointer to the tuning(7) manpage there, too.

Just my two cents.

Best regards
   Oliver

-- 
Oliver Fromme,  secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing
Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd
Any opinions expressed in this message may be personal to the author
and may not necessarily reflect the opinions of secnetix in any way.

"Documentation is like sex; when it's good, it's very, very good,
and when it's bad, it's better than nothing."
        -- Dick Brandon



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