-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 This question came up on the coreutils list:
Does cygwin provide any support for sparse files on NTFS volumes that support it? lseek() could be patched to use FSCTL_SET_ZERO_DATA when a seek jumps past the end of a file open for writing, but there is still the issue of when that file is given the FSCTL_SET_SPARSE attribute. - -------- Original Message -------- Subject: Re: cp command - problem with sparse Date: Tue, 01 Feb 2005 10:17:01 +0000 From: jay AT excession DOT spiral-arm DOT org (James Youngman) To: RE <eicher_und_bergmann AT yahoo DOT de> CC: bug-coreutils AT gnu DOT org References: <EGECIPGBMFENJDOHIEMIAEMGCBAA DOT eicher_und_bergmann AT yahoo DOT de> On Mon, Jan 31, 2005 at 05:30:22PM +0100, RE wrote: > "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 an 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) 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. See http://www.ntfs.com/ntfs-sparse.htm and http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/base/fsctl_set_zero_data.asp _______________________________________________ Bug-coreutils mailing list Bug-coreutils@gnu.org http://lists.gnu.org/mailman/listinfo/bug-coreutils - -- Life is short - so eat dessert first! Eric Blake [EMAIL PROTECTED] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (Cygwin) Comment: Public key at home.comcast.net/~ericblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFB/4jI84KuGfSFAYARArbqAKC8oMiDsvW93G9xZpZtjcIcFxPeRACeNti6 iWWYrjHN7i1YlvfKMNLqps8= =CLd3 -----END PGP SIGNATURE----- -- 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/
