Re: [gentoo-user] Re: Reading a DVD as an ISO image

["José Romildo Malaquias" <j.romildo@gmail.com>]

On Tue, Nov 17, 2009 at 04:54:20PM +0000, Grant Edwards wrote:
> On 2009-11-17, Marcus Wanner <marcusw@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.

Romildo