md5sum on CD

Moniz Family john.moniz-rieW9WUcm8FFJ04o6PK0Fg at
Thu Nov 24 19:39:59 UTC 2005

D. Hugh Redelmeier wrote:

>| From: Moniz Family <john.moniz-rieW9WUcm8FFJ04o6PK0Fg at>
>| 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:
> 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 
>- 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.

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