Date: Sun, 1 Jul 2001 17:02:54 +0200 (MET DST) From: Joerg Schilling <schilling@fokus.gmd.de> To: mckay@thehub.com.au, schilling@fokus.gmd.de Cc: freebsd-scsi@freebsd.org, ken@kdm.org Subject: Re: Problems reading burned CDs Message-ID: <200107011502.RAA16964@fokus.gmd.de>
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>From mckay@thehub.com.au Sun Jul 1 16:50:52 2001
>On Sunday, 1st July 2001, Joerg Schilling wrote:
>>>From ken@panzer.kdm.org Sun Jul 1 06:01:32 2001
>>
>>>On Thu, Jun 28, 2001 at 22:25:18 +1000, Stephen McKay wrote:
>>>> Actually, the difference is pressed vs burned CDs.
>>It is really a bad idea to use dd to read a CD.
>I think it's important that the raw CD be presented in a fully readable
>format. Then dd (and everything else) will work properly.
Please don't try to do this!
It is a known fact that these problems with TAO CD's exist.
If you change FreeBSD, then it would behave different from an other OS.
As I already said: you should not read a CD with dd but with 'readcd'.
readcd allows you to specify sectors=from-to to exclude these run-out
sectors. Future versions may even do this automatically.
>>>> Is there any way around these problems with SCSI CD drives?
>>
>>Read README.verify & README.copy for a long answer....
>I'm still digesting this information (from the cdrecord program, if anyone
>else is looking for them). I am assuming that 2 (or more) unreadable
>sectors are added, not that I lose 2 sectors of data. Right?
correct.
>>>Just out of curiosity, what did you use to burn the CD? cdrecord?
>We might either have to lie about the capacity (so that every reported byte
>can be read), or deal specially with the run out blocks (by faking them
>as nulls).
Again: please don't do that! You would only create confusion.
All people who know CD standards known about this Authors of CD drivers and
ISO-9660 filesystem should know it.
>>># cdrecord dev=1,4,0 -toc
>>>Cdrecord 1.9 (i386-unknown-freebsd4.2) Copyright (C) 1995-2000 Jörg Schilling
>>
>>A really old one.....
>Old software lives on! I'm still using 1.8, by the way.
>It also looks like you renamed your suite to: cdrtools. I expect the
>cdrecord port maintainer didn't notice.
I don't know who this is and I expect that a port maintaner is on the
right mailing lists where this change has been discussed at least for 2 years.
Jörg
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.gmd.de (work) chars I am J"org Schilling
URL: http://www.fokus.gmd.de/usr/schilling ftp://ftp.fokus.gmd.de/pub/unix
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