Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sources.redhat.com/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sources.redhat.com/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Message-ID: <16072.6666.10124.338022@gargle.gargle.HOWL>
Date: Sun, 18 May 2003 16:40:58 -0700
From: Martin Buchholz <martin AT xemacs DOT org>
To: "Max Bowsher" <maxb AT ukf DOT net>
Cc: <cygwin AT cygwin DOT com>
Subject: Re: SPARSE files considered harmful - please revert
In-Reply-To: <003901c31d8c$6ec495f0$78d96f83@pomello>
References: <16072 DOT 892 DOT 778395 DOT 24290 AT gargle DOT gargle DOT HOWL>
	<003901c31d8c$6ec495f0$78d96f83 AT pomello>
Reply-To: martin AT xemacs DOT org

>>>>> "Max" == Max Bowsher <maxb AT ukf DOT net> writes:

Max> May I suggest a middle road? Why not let sparse files be configurable as a
Max> $CYGWIN option? This would allow those users who actually want them to
Max> enable them with minimal effort, but keep them off for most users.

I suspect that SPARSE files are genuinely useful, when storing large
files that have holes in them.  But I can't imagine one ever wanting
to use SPARSE for all files, because most files aren't like that.  So
I don't think sparseness is a good candidate for being put into
$CYGWIN.

We could have a much cleverer implementation of sparseness, if we kept
statistics on the number and size of zero bytes in a file while it was
being written.  When we did the close(), we could automatically
transform it into a sparse file.  But I don't think even that should
be the default behavior, because it would make all IO slower.

A program I might actually use myself is one that examines a file on
disk to see if it could be stored more compactly as a sparse file, and
transform it if that were the case.  Give it a -r option, and you
would have a "disk optimizer".  You can do something similar on Unix.

Martin

--
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
Problem reports:       http://cygwin.com/problems.html
Documentation:         http://cygwin.com/docs.html
FAQ:                   http://cygwin.com/faq/