md5sum on CD

[Moniz Family]

Moniz Family wrote:

> D. Hugh Redelmeier wrote:
>
>> | From: Moniz Family <john.moniz-rieW9WUcm8FFJ04o6PK0Fg at public.gmane.org>
>> | | I'm having some problems burning CDs and am trying to check 
>> whether it's the
>> | burner or the CDs.
>>
>> You've gotten some good advice -- like using the right hash.
>>  
>>
>
> Some excellent advice, thanks to all.
>
>> Checking on a file-by-file basis is not really good enough.  There are
>> things that are not inside files.  For example, metadata.  Also (I
>> think) boot records.
>>
>> But there is another problem that you might well be hitting.
>>
>> See, for example:
>>  https://www.redhat.com/archives/fedora-list/2005-March/msg02774.html
>>  https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=151088
>>
>> Summary:
>>
>> The Linux IDE CD driver in 2.6 tries to read ahead, even past the end 
>> of the
>> CD or DVD.  Even when the program issuing the original read request 
>> was only
>> trying to read legitimate parts of the disc (albeit near the end).
>> The result is spurious I/O errors and read failures.
>> It does not seem that this driver bug is going to be fixed soon.
>>
>>
>> To work around this problem, I wrote the two shell scripts that I 
>> have attached.
>>
>> - isopad: add enough padding to prevent ide-cd read-ahead getting
>>  into trouble (can also remove the padding)
>>
>> - isoburn: burn and check a .iso.  Uses isopad.
>>  Warning: you may have to adjust the settings of the shell variables
>>  "drive", "device", and "speed" to match your environment.
>>
>
> The only time I was using the 2.6 kernel was when trying to install 
> Fedora Core 4. Maybe that's why my Disk 3 failed the media test??? All 
> of the burns and checks were done with RH9 and kernel 2.4.
>
> One thing I didn't try with cdrecord was the pad option.
>
> Thanks for the scripts. You're taking me a little past my experience 
> level, but I may be able to use them.
>
> John.

I just burned a Knoppix ISO immage and used the -pad option (-pad 
padsize=15s). I gather the checksum would be changed after using the pad 
option? It did on mine anyway.

John.
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