Date: Sun, 4 Jan 2004 16:59:57 +0000 From: Scott Mitchell <scott+freebsd@tuatara.fishballoon.org> To: "W. Sierke" <ws@au.dyndns.ws> Cc: freebsd-questions@FreeBSD.org Subject: Re: How to create .iso file image of cdrom (atapi)? Message-ID: <20040104165957.GB2884@fishballoon.org> In-Reply-To: <02f501c3d2de$c5064140$8464a8c0@ovirt.dyndns.ws> References: <02f501c3d2de$c5064140$8464a8c0@ovirt.dyndns.ws>
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On Mon, Jan 05, 2004 at 02:51:12AM +1030, W. Sierke wrote: > "Scott Mitchell" wrote: > > You want to use /dev/acd0c - the 'c' partition covers the whole disk. > > Something like: > > > > dd if=/dev/acd0c of=foo.iso bs=64k > > Ah! Thanks for that. The bs argument is crucial, I hadn't thought to try > anything further when without it I got: > > dd: /dev/acd0c: Invalid argument The block size of a data CD is 2048 bytes, so I guess you'd need to specify some multiple of 2048 for dd. Bigger reads should improve performance somewhat, hence my use of 64k. On the other hand, for audio CDs the block size is 2352, as discussed in the handbook: http://www.uk.freebsd.org/doc/en_US.ISO8859-1/books/handbook/creating-cds.html > I let myself be led astray into thinking that there must be something amiss > with using that device. So if the 'c' partition is the whole disk, what's > the 'a' partition, out of curiosity? On an ISO9660 data CD, the 'a' partition appears to cover the whole disk, just like 'c'. That might change if you had, say, a UFS filesystem on there, or no filesystem at all, just raw data of some kind. A data CD won't in general have a BSD disklabel on it, so I assume disklabel is faking up an 'a' partition to cover the whole disk when I do: (504) tuatara:~ $ disklabel acd0 # /dev/acd0c: type: unknown disk: acd0 label: unknown flags: removeable bytes/sector: 2048 sectors/track: 100 tracks/cylinder: 1 sectors/cylinder: 100 cylinders: 3231 sectors/unit: 323014 rpm: 300 interleave: 1 trackskew: 0 cylinderskew: 0 headswitch: 0 # milliseconds track-to-track seek: 0 # milliseconds drivedata: 0 1 partitions: # size offset fstype [fsize bsize bps/cpg] a: 323014 0 4.2BSD 0 0 0 # (Cyl. 0 - 3230*) boot block size 0 super block size 0 Cheers, Scott -- =========================================================================== Scott Mitchell | PGP Key ID | "Eagles may soar, but weasels Cambridge, England | 0x54B171B9 | don't get sucked into jet engines" scott at fishballoon.org | 0xAA775B8B | -- Anon
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