On Wed, Nov 18, 2009 at 09:36:03AM -0600, Paul Hartman wrote: > 2009/11/18 José Romildo Malaquias <j.romi...@gmail.com>: > > On Tue, Nov 17, 2009 at 04:54:20PM +0000, Grant Edwards wrote: > >> On 2009-11-17, Marcus Wanner <marc...@cox.net> wrote: > >> > >> > My guess is that he has a slow internet connection, he > >> > downloaded a large iso, burned it, deleted it, and now wants > >> > to get the iso back without downloading it again, but he has > >> > access to the checksum/filesize of the original iso from the > >> > place he downloaded it, and when he makes an iso, the > >> > checksum/filesize does not match. > >> > >> In my experience that happens because one or the other of the > >> images has "extra" garbage blocks past the end of the actual > >> ISO filesystem image. If you look at the ISO filesystem header > >> and find the actual size of the image, it's probably smaller > >> than the "image file". If you only compare the bytes within > >> the ISO image itself, I bet the two will match. > > > > In fact the size of the iso images obtained with dd and with cdread are > > a little bit larger than the original one. The iso image obtained by > > mkisofs on the mounted disc (with the udf filesystem type) are of the > > right size, but still not identical to the original. > > This webpage has some info about comaring ISO images to burnt discs > and a possible solution: > http://twiki.org/cgi-bin/view/Wikilearn/CdromMd5sumsAfterBurning
Thanks for the link. As I know the size and the sha1sum of the original ISO image, I succeeded in creating an identical ISO image from the dvd disc with the command: dd if=/dev/dvd | head -c 4610877440 > /var/tmp/image2.iso Is it possible to do something similar using readcd instead of dd? Romildo
