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From:	"John Vincent" <jpv50 AT hotmail DOT com>
To:	cygwin AT cygwin DOT com
Subject:	Re: SPARSE files considered harmful - please revert
Date:	Mon, 19 May 2003 19:26:22 +0000
Mime-Version:	1.0
Message-ID:	<Law10-F95uUaJ0gmkLG00033be2@hotmail.com>
X-OriginalArrivalTime:	19 May 2003 19:26:22.0425 (UTC) FILETIME=[87F35C90:01C31E3C]

You say that any areas that are seeked over should be sparse as well. That 
is true on many Unix/Linux file systems. I've not seen anything to suggest 
it's true on NTFS though, have you?


From: "Max Bowsher" <maxb at ukf dot net>
To: <cygwin at cygwin dot com>
Date: Mon, 19 May 2003 19:54:19 +0100
Subject: Re: SPARSE files considered harmful - please revert
References: <Law10-F79o4cWScPAA600033a95 AT hotmail DOT com>

--------------------------------------------------------------------------------

John Vincent wrote:
>
>I looked up sparse files on MSDN and found the following link:
>
>
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/base/sparse_file_operations.asp
>
>The most interesting thing is that a sparse file is only sparse if the
zeros
>in the file are written with a special operation. I strongly suspect that
>the patch to support sparse files introduced in cygwin is incorrect (or at
>least incomplete)

Areas that are simply seeked over, and never written to, should be sparse as
well.

Anyway:

Based on the posted numbers, global use of sparse files is a bad idea. Can
we conditionalize sparse files on a $CYGWIN option? (Or something else, I
don't mind, but the important thing is that it should not be on by default.)

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