Re: howto verify burn?
On Wed, Mar 05, 2003 at 11:03:28AM -0800, Craig Dickson wrote:
> bob parker wrote:
>
> > On Thu, 6 Mar 2003 04:22, Ray wrote:
> > > how do i verify that the burned cd is correctly burned?
> > >
> > > i burned a set of Debian 3.0r1 cds and have md5sums of the isos, but they
> > > don't match the output of
> > > md5sum -b /dev/cdrom
> >
> > Not really an expert on what happens on cds but I belive it has something to
> > do with the some extra nulls packing it out to the end of a 2048 block or
> > something like that.
> >
> > In any case the actual cd generally has a different md5sum than the iso.
> >
> > One way:
> > cat /dev/cdrom > test.iso
> > md5sum test.iso
> > md5sum original.iso
Yes they are different :-)
> Isn't
>
> md5sum /dev/cdrom
>
> equivalent to
>
> cat /dev/cdrom >test.iso
> md5sum test.iso
>
I think so. But there are junk sectors added when creating data on CD.
http://www.debian.org/doc/manuals/reference/ch-tune.en.html#s9.3.7
So read exact # of sectors back to harddisk. Run MD5 or cmp :-)
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