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AW: cp command - problem with sparse
From: |
RE |
Subject: |
AW: cp command - problem with sparse |
Date: |
Wed, 2 Feb 2005 11:11:38 +0100 |
Hi Eric,
Thanks a lot for your mail. I just tried to send a mail to Corinna who
answered you in the list but I am afraid that I am black-listed with her
account and I don't know how to solve the problem. I already tried to get
white-listed by sending a mail to
address@hidden , but it
didn't work for me.
Maybe you can answer my question or help me with my "sparse problem" which I
am quoting in the following once again. [BTW I don't know if the patch you
sent me will be needed, but if yes, I would not know how to apply it ;-((( ]
Well, I am not a programmer but I am looking for a solution for the
following. And I still think that cp.exe from fileutils/coreutils might do
the job. But so far I wasn't successful.
I have files on my HD that contain large amounts of zeroes (between 4 and
100 MB of zeroes) and I want to convert them into sparse files. I already
tried the GNU fileutils with their cp command. They say that it converts
standard files into sparse files by using the command
"cp --sparse=always c:\test.cfg c:\test2.cfg"
Everything works fine with that cp command, except the fact that I do not
get a sparse file. Even when I copy a sparse file, the sparse attribute is
no longer present in the copy and the occupied space on my HD is the same as
with the original file.
What am I doing wrong?
I tried already different PCs with NTFS (OS = Win2k SP4)
Your help and assistance would be appreciated very
much.
Thanks and regards,
Rolf
-----Ursprüngliche Nachricht-----
Von: Eric Blake [mailto:address@hidden
Gesendet: Mittwoch, 2. Februar 2005 04:17
An: James Youngman
Cc: RE; address@hidden
Betreff: Re: cp command - problem with sparse
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According to James Youngman on 2/1/2005 3:17 AM:
>
> Unix systems automatically generate sparse files when programs seek
> forwards on their output file. There is no need to have a "sparse"
> attribute. This is what coreutils' "cp" does.
>
> Windows and NTFS don't work in this way. Under NTFS, there is, as you
> say, a "sparse" attribute which must be set. GNU coreutils runs on
> Windows under Cygwin and am not sure if Cygwin exposes any form of API
> which might allow cp to set the sparse attribute. It's certainly a lot
more complex to do this under Windows.
>
According to the cygwin mailing list,
http://sources.redhat.com/ml/cygwin/2005-02/msg00013.html, cygwin already
supports sparse files when you do lseek beyond EOF during writes. The
trick, however, is that NTFS on Windows XP does not create a hole until
128k.
Therefore, this patch is needed in the testsuite to turn a SKIP into a
PASS on cygwin:
2005-02-01 Eric Blake <address@hidden> (tiny change)
* tests/du/8gb: Detect sparse files on NTFS under cygwin.
- --
Life is short - so eat dessert first!
Eric Blake address@hidden
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- cp command - problem with sparse, RE, 2005/02/01
- Re: cp command - problem with sparse, James Youngman, 2005/02/01
- Re: cp command - problem with sparse, Eric Blake, 2005/02/02
- Re: cp command - problem with sparse, Jim Meyering, 2005/02/02
- Re: cp command - problem with sparse, Andreas Schwab, 2005/02/02
- Re: cp command - problem with sparse, Jim Meyering, 2005/02/02
- Re: cp command - problem with sparse, Andreas Schwab, 2005/02/02
- Re: cp command - problem with sparse, Jim Meyering, 2005/02/02
- Re: cp command - problem with sparse, Andreas Schwab, 2005/02/02
- AW: cp command - problem with sparse,
RE <=
- Re: AW: cp command - problem with sparse, Eric Blake, 2005/02/02
Re: cp command - problem with sparse, Eric Blake, 2005/02/03