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(!) cd-writing mini-howto

Answer By Chris Coyle

I found the "CD-Writing with an ATAPI CDR Mini-HOWTO" (http://linuxgazette.net/issue57/stoddard.html) very helpful. Thank you.
Here are a couple of suggestions which other readers who are interested in the same subject may find useful.
  1. (very minor) I think it should be /etc/modules.conf not /etc/conf.modules
  2. I just discovered that the ide-scsi module in kernel 2.2.17 (from RH rpms I just DL'ed), either has a big problem, or else it is significantly incompatible with previous kernels.
Here's what happened:
I DL'ed and installed the RH rpms for kernel 2.2.17-14. These were recommended in a security advisory. I kept my previous kernel (2.2.16) installed just in case, adding a new section to /etc/lilo.conf by copying the previous one, mutatis mutandis. Then I ran lilo and rebooted. At first everything appeared to be OK with the new kernel, but then I tried to mount my cd-rom and it failed, giving the message 
mount: wrong fs type, bad option, bad superblock
on /dev/cdrom or too many mounted filesystems
While I was searching for the cause of this I remembered that I had set up my cd-recorder to use ide-scsi.
My regular cd-rom reader is hdc and the cd-recorder is hdd. Following the directions in your mini-howto, I had inserted
append="hdd=ide-scsi"
and this I had copied faithfully into the new 2.2.17 section. When I removed it and rebooted, I found I could mount the cd-rom again. Then I put the line back in and rebooted.
This time I looked at what scsi devices were detected. Eureka! By looking at dmesg and also by using "cdrecord -scanbus" I discovered that the ide-scsi module had taken over both hdc and hdd, even though I requested only hdd. I asked for help on comp.os.linux.misc and within hours someone else confirmed the same thing, namely
"...if you have two devices on an IDE channel, and one of them is under ide-scsi emulation, it's better to treat both of them as if they were under ide-scsi emulation.
I don't know if this is due to a an error or a design change, but the work-around was quite straightforward.
The only tricky bit was that I wanted to be able to boot 2.2.16 so I had to devise a way to make both kernels boot up in a state where they could use the same devices and configuration files. My solution is as follows:
  1. Change the lines in /etc/lilo.conf to
    append="hdc=ide-scsi hdd=ide-scsi"
    in both kernel sections.
  2. Move the /dev/cdrom link from hdc to scd0.
  3. Change the scsi configuration for the cd-recorder in /etc/cdrecord.conf to 0,1,0 (since it is now the second scsi host).
After all that I am finally back to the point where I can mount the cd-rom and use the cd-recorder, with either 2.2.16 or 2.2.17 kernel.

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Published in issue 65 of Linux Gazette April 2001
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