Date: Sun, 23 Sep 2001 08:15:08 -0500 From: Mike Meyer <mwm@mired.org> To: swear@blarg.net (Gary W. Swearingen) Cc: questions@freebsd.org Subject: Re: Why is ISO CD one block bigger than ISO file? Message-ID: <15277.57436.871360.339424@guru.mired.org> In-Reply-To: <114626803@toto.iv>
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Gary W. Swearingen <swear@blarg.net> types: > I've got a 4.4R ISO file. Size is 324368*2048. I did > "burncd -f /dev/acd0c -s 8 data 4.4R.iso fixate" and then did > "dd if=/dev/acd0a bs=2k | wc" which showed the CD was one 2048-byte > block bigger than the ISO file. I used "dd" and "md5" to verify that > the first 324368 blocks of the CD were the same as the ISO file. > Why the extra block? Not sure, unless it's something with the cd build process. I would recommend "dd if=/dev/acd0c bs=2k of=/dev/null" to get a count as better than piping things through wc. > Also: Is there ANY difference between /dev/acd0a and /dev/acd0c between > the name and the minor number? May they always be used interchangeably? ISO disks don't really have paritition tables in the traditional sense. The -stable cd drivers fake one that covers the first track and provides the a and c partition. As such, they're always going to be the same and can be used interchangeable. This is an acknowledged hack, but probably won't go away unless CDROMS with with multiple data tracks on them come into common use. Be warned that other types of CDROMs can have real parition tables on them, and thus have a and c partitions that are *not* identical. <mike -- Mike Meyer <mwm@mired.org> http://www.mired.org/home/mwm/ Q: How do you make the gods laugh? A: Tell them your plans. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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