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Re: sha1sum problems :-( [kind of SOLVED]

> Marko Vojinovic wrote:
>> Ok, I downloaded the brand-new Fedora 8 iso file:
>> [vmarko sith ~]$ sha1sum Fedora-8-i386-DVD.iso
>> 782a0e80de1b8e9f24e10e40055cc1b545390cbd  Fedora-8-i386-DVD.iso
>> After burning it to two dvd's on two different machines (one Windows,
>> the
>> other Linux) using different software (Nero and K3B), I get:
>> [vmarko sith ~]$ sha1sum /dev/dvd
>> 04e39c4be1cf577b98a8b94ff61bdb60252ec6cb  /dev/dvd
>   "sha1sum /dev/dvd" is not a reliable way to read a disc, though it may
> work on some hardware.  Try using the rawread script at
> http://www.troubleshooters.com/linux/coasterless.htm
> instead.  This uses the isoinfo command to determine how big the ISO
> file is, then runs a dd command that attempts to read exactly that much
> off the drive.  If this still fails, then please report back.  I'm
> currently seeing a return of the old mediacheck problem (linux readahead
> bug).

Ok, I followed advice from that link, and it actually works:

[vmarko sith ~]$ ./rawread /dev/dvd | sha1sum
dd if=/dev/dvd bs=2048 count=1672241 conv=notrunc,noerror
1672241+0 records in
1672241+0 records out
3424749568 bytes (3.4 GB) copied, 490.465 s, 7.0 MB/s
782a0e80de1b8e9f24e10e40055cc1b545390cbd  -

So it *seems* that everything is ok with the discs. Now I have to figure
out why those two machines do not boot from either of them. But that is
another issue...

I was not aware that sha1sum&friends have problems to determine the actual
size of data when reading optical media. This is a valuable lesson!

Thanks for help! ;-)


Marko Vojinovic
Institute of Physics
University of Belgrade
e-mail: vmarko phy bg ac yu

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