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Re: linux kernel error reading end of cd/dvd

>From: Volker Kuhlmann <hidden@paradise.net.nz>


>(I scripted that a long time ago). In the mid nineties it was necessary
>to use cdrecord -pad to make linux read all the files, described as
>read-ahead bug in linux's iso9660 driver in the cdrecord man page. When
>I checked again a few years ago it was still necessary to use -pad, so
>I kept on always using it as a matter of course. This year I find that
>cdrecord -pad is no longer enough, and the same problem shows up again.
>It affects cds and dvds, and all pressed commercial cds cerated on
>non-linux systems. The problem shows up at varying degrees, I suspect
>it has to do with the modulus of the number of filesystem blocks of the
>particular disk. Several times I was unable to completely read the
>filesystem from cds, I/O error 2 or more blocks beore its end no matter
>what I did. Often it helps to use dd skip= to only read the last 10
>filesystem blocks, and it works. Reading all filesystem blocks from the
>beginning, or from a suitably large distance from the end - I/O error.
>Sometimes the problem goes away when turning DMA off for the cd/dvdrom
>drive, but that is not an acceptable way of running it. I really doubt
>it's hardwaredependent, as I have seen it on 3 totally different
>machines now. Kernels 2.4.19, 2.4.20. It doesn't help that read
>problems on a cd/dvd can cause the IDE bus, if not the system, to lock
>up for some time. Appending 2MB of zeroes to the disk image file before
>burning makes it disappear reliably. I keep on wasting CDs because I
>forget to append that dummy data.

This is wrong.

There is no need to use -pad!

If you use unapropriate software like "dd" and don't even send a problem
report, it is impossible to help you :-(


mkisofs now adds paddinf for a long time ....

Unfortunately, the Linux kernel hackers constantly add new bugs to the kernel :-(
It would really be nice if they woutl start to listen to people who know how to 
do things right.


 EMail:joerg@schily.isdn.cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin
       js@cs.tu-berlin.de		(uni)  If you don't have iso-8859-1
       schilling@fokus.fraunhofer.de	(work) chars I am J"org Schilling
 URL:  http://www.fokus.fraunhofer.de/usr/schilling ftp://ftp.berlios.de/pub/schily

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