From owner-freebsd-fs@FreeBSD.ORG  Mon Jun 13 12:26:05 2011
Return-Path: <owner-freebsd-fs@FreeBSD.ORG>
Delivered-To: freebsd-fs@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 2D7E8106564A
	for <freebsd-fs@freebsd.org>; Mon, 13 Jun 2011 12:26:04 +0000 (UTC)
	(envelope-from brde@optusnet.com.au)
Received: from mail05.syd.optusnet.com.au (mail05.syd.optusnet.com.au
	[211.29.132.186])
	by mx1.freebsd.org (Postfix) with ESMTP id 56B8B8FC13
	for <freebsd-fs@freebsd.org>; Mon, 13 Jun 2011 12:26:04 +0000 (UTC)
Received: from c122-106-165-191.carlnfd1.nsw.optusnet.com.au
	(c122-106-165-191.carlnfd1.nsw.optusnet.com.au [122.106.165.191])
	by mail05.syd.optusnet.com.au (8.13.1/8.13.1) with ESMTP id
	p5DCQ0In016212
	(version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO);
	Mon, 13 Jun 2011 22:26:01 +1000
Date: Mon, 13 Jun 2011 22:26:00 +1000 (EST)
From: Bruce Evans <brde@optusnet.com.au>
X-X-Sender: bde@besplex.bde.org
To: =?UTF-8?Q?=C5=A0imun_Mikecin?= <numisemis@gmail.com>
In-Reply-To: <BANLkTinGNetJn=W9RuoUp44QGyRqHQ1wvw@mail.gmail.com>
Message-ID: <20110613222215.J1792@besplex.bde.org>
References: <F21D6DCDBA494B4A9FDF20A13BC4947A@multiplay.co.uk>
	<20110613094803.GA10290@icarus.home.lan>
	<BANLkTikDXHwk_P-6rdoZYRVcqGnOCwXoMg@mail.gmail.com>
	<3DA28334D5774636A0DDEB48D8A43A91@multiplay.co.uk>
	<BANLkTinGNetJn=W9RuoUp44QGyRqHQ1wvw@mail.gmail.com>
MIME-Version: 1.0
Content-Type: MULTIPART/MIXED; BOUNDARY="0-384147912-1307967960=:1792"
Cc: freebsd-fs@freebsd.org
Subject: Re: Impossible compression ratio on ZFS
X-BeenThere: freebsd-fs@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Filesystems <freebsd-fs.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-fs>,
	<mailto:freebsd-fs-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-fs>
List-Post: <mailto:freebsd-fs@freebsd.org>
List-Help: <mailto:freebsd-fs-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-fs>,
	<mailto:freebsd-fs-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 13 Jun 2011 12:26:05 -0000

  This message is in MIME format.  The first part should be readable text,
  while the remaining parts are likely unreadable without MIME-aware tools.

--0-384147912-1307967960=:1792
Content-Type: TEXT/PLAIN; charset=X-UNKNOWN; format=flowed
Content-Transfer-Encoding: QUOTED-PRINTABLE

On Mon, 13 Jun 2011, [UTF-8] =C5=A0imun Mikecin wrote:

> 2011/6/13 Steven Hartland <killing@multiplay.co.uk>
>
>> Using 'du' for file sizes (without -A option) is wrong in the first plac=
e.
>>> Any program or script that is using it in such a way is broken and shou=
ld
>>> be
>>> corrected.

You mean that any script that uses du with the -A option is broken.  -A
just shows the file size in bad units.

>> That's not true, -A displays the apparent size not the actual disk usage
>> which is what we want.
>
> Disk usage is not equal to file size. 'ls -al' shows file size, 'du' show=
s
> disk usage.
> Use the one you need, but don't expect them to be the same thing.

Indeed, the file size is only vaguely related to the disk usage.  Normal
du shows disk usage including increases of it due to metadata and
decreases of it due to compression or sparseness (which is a particular
type of compression).  du -A might be useful if the file is to be
copied to another file system with no compression at all.

Bruce
--0-384147912-1307967960=:1792--