Date: Mon, 3 Nov 2008 18:12:14 +0100 From: Fabian Keil <freebsd-listen@fabiankeil.de> To: freebsd-questions@freebsd.org Subject: Re: copying 'holey' files ... Message-ID: <20081103181214.1adafa2b@fabiankeil.de> In-Reply-To: <F051A44CEADE0E79AEA7654E@ganymede.hub.org> References: <F051A44CEADE0E79AEA7654E@ganymede.hub.org>
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[-- Attachment #1 --] "Marc G. Fournier" <scrappy@hub.org> wrote: > I have a disk img for qemu that is 4G, but disk usage is only 650M ... due to > how the image is created, it will grow to 4G, but only uses as much as it needs > ... but, if I run a simple 'cp' on the file, it goes from: > > image: debian.img > file format: raw > virtual size: 4.0G (4294967296 bytes) > disk size: 652M > > to: > > image: dtc.img > file format: raw > virtual size: 4.0G (4294967296 bytes) > disk size: 4.0G > > Is there a way of moving things around such that it *maintains* the holes, > instead of fills them in? Quoting dd(1): | conv=value[,value ...] | Where value is one of the symbols from the following list. [...] | sparse If one or more output blocks would consist solely of | NUL bytes, try to seek the output file by the required | space instead of filling them with NULs, resulting in a | sparse file. I haven't actually tested it with qemu images, though. Fabian [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (FreeBSD) iEYEARECAAYFAkkPMO4ACgkQBYqIVf93VJ1AngCfYPUvWuqNSLF4IZdINybQvgy8 MfEAoKvWf0GAzXA3PrWcKHWwh/ni1udt =jCjf -----END PGP SIGNATURE-----
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