md5sum on CD

[Moniz Family]

Sy Ali wrote:

>On 11/21/05, Moniz Family <john.moniz-rieW9WUcm8FFJ04o6PK0Fg at public.gmane.org> wrote:
>  
>
>>I'm having some problems burning CDs and am trying to check whether it's
>>the burner or the CDs. One of the things I'd like to do, but can't
>>figure out from the man pages, is to run an md5sum on the entire CD to
>>compare to the ISO image I downloaded. Is there a way to do this without
>>first making another ISO image from the CD? If so, would it give the
>>same result anyway?
>>
>>On a related note, I downloaded all 4 ISOs for Fedora Core 4, but none
>>of them had the same checksum as specified on the mirror site. I tried
>>downloading Disk 1 a second time and had the exact same (but incorrect)
>>checksum as the first try. I asked my neighbour to download Disk 1 and
>>he got the exact same (but incorrect) checksum as I did. Coincidence???
>>Is it a common occurence for the checksum to be wrong, but consistent? I
>>think I tried different mirrors each time.
>>    
>>
>
>md5sum of a cd:
>dd if=/dev/cdrom bs=2048 | md5sum
>
>>From http://www.sun.com/bigadmin/features/articles/burn_iso_images.html
>[quote]
>If I had not specified -dao (session at once mode) and taken the
>cdrecord default recording mode (track at once), the following would
>have happened:
>
># md5sum /dev/cdrom
>md5sum: /dev/cdrom: Input/output error
>[/quote]
>
>There could be an issue with the way you were burning the cd.
>  
>
Thanks for the link Sy, I think that's what was creating the burn 
problem. I used the -dao option and now all the CDs have the correct 
checksum, once I used the right program (sha1sum). I get the same error 
as above without -dao.

Most of the disks passed the Fedora media check, except for Disk 3, even 
after a couple of tries. The checksum is good (sha1sum /dev/cdrom), but 
Fedora gives it a Fail. Odd! Maybe I should try the -pad option as well.

John.
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