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Re: SPARSE files considered harmful - please revert



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@hotmail.com>

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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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