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<H3 align="left"><img src="../../gx/dennis/qbubble.gif" 
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	>/dev/scd0 is not a valid block device?</H3>


<p><strong>From Simeon Nevel 
</strong></p> 

<p align="right"><strong>Answered By  Mike Martin, Neil Youngman, Heather Stern
</strong></p>

<blockquote><em><font color="#000066">With our kind thanks for publication permission.
 -- Heather</font></em></blockquote>
<P><STRONG>
Dear Answer Gang,
</STRONG></P>
<P><STRONG>
I'm trying to get my cd and cdrw working in RH7.3. I've read through
both articles on CD Writing in issue 57 and looked at the CD-Rom HOWTO
as well.
</STRONG></P>
<P><STRONG>
I've got to proper invocation in grub:
</STRONG></P>

<pre><strong>title Red Hat Linux (2.4.18-3)
   root (hd1,0)
   kernel /vmlinuz-2.4.18-3 ro root=/dev/hdb7 hdc=ide-scsi hdd=ide-scsi
   initrd /initrd-2.4.18-3.img
</strong></pre>
<P><STRONG><CODE>
lsmod shows that the various ide-scsi modules are loaded:
</CODE></STRONG></P>

<pre><strong> Module                  Size  Used by    Not tainted
  [other modules snipped for brevity]
  sr_mod                 16920   0  (autoclean) (unused)
  autofs                 12164   0  (autoclean) (unused)
  ide-scsi                9664   0
  scsi_mod              108608   2  [sr_mod ide-scsi]
  ide-cd                 30272   1
  cdrom                  32192   0  [sr_mod ide-cd]
</strong></pre>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
	HEIGHT="28" WIDTH="50" BORDER="0"
	> [Mike M.] 
not sure whether ide-cd should be getting loaded
you may want to experiment by unloading the scsi modules and
reloading in turn (sg and sd may be an idea)
</blockQuote>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
	HEIGHT="28" WIDTH="50" BORDER="0"
	> [Neil Youngman] 
Is this bit from the CD-Writing HOWTO relevant?
</blockQuote>
<blockQuote><DL><DT>
Example configuration for <TT>/etc/modules.conf</TT> from
<DD><A HREF="http://www.tldp.org/HOWTO/CD-Writing-HOWTO-2.html"
	>http://www.tldp.org/HOWTO/CD-Writing-HOWTO-2.html</A>
</DL></blockQuote>

<TABLE WIDTH="95%" BORDER="1" BGCOLOR="#FFFFCC"><TR><TD>
<p align="center">...............</p>
<blockQuote>
make sure you include the
options-line from the next listing. The last three lines of that listing
are generally suggested to further automate the loading of the required
modules.
</blockQuote>

<blockquote><pre>options ide-cd ignore=hdb            # tell the ide-cd module to ignore hdb
alias scd0 sr_mod                    # load sr_mod upon access of scd0
#pre-install ide-scsi modprobe imm    # uncomment for some ZIP drives only
pre-install sg     modprobe ide-scsi # load ide-scsi before sg
pre-install sr_mod modprobe ide-scsi # load ide-scsi before sr_mod
pre-install ide-scsi modprobe ide-cd # load ide-cd   before ide-scsi Listing:
</pre></blockquote>
<p align="center">...............</p>
</TD></TR></TABLE><blockQuote>
If that doesn't help then have a look at the output from dmesg and see if it
offers any clues.
</blockQuote>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
	HEIGHT="28" WIDTH="50" BORDER="0"
	> [Heather] 
autofs is unrelated.  Unless you also have another ATAPI CD which is not
supposed to be handled by scsi, you definitely have too many modules loaded.
</blockQuote>
<blockQuote>
The kernel support notes (very easy to read in "make menuconfig", a
little plainer in <TT>/usr/src/linux/Documentation/Configure.help</TT>) make it
clear that:
</blockQuote>

<TABLE WIDTH="95%" BORDER="1" BGCOLOR="#FFFFCC"><TR><TD>
<p align="center">...............</p>
<blockQuote><BLOCKQuote>
If both ATAPI and generic scsi support is provided, the
native services will be used.
</BLOCKQuote></blockQuote><p align="center">...............</p>
</TD></TR></TABLE>
<blockQuote>
For my IDE/ATAPI cd-recorder, I don't have any of these loaded automatically.
I do have the append line (in my case, 'hdd=ide-scsi').  When I:
</blockQuote>

<blockquote><pre>	modprobe ide-scsi
</pre></blockquote>
<blockQuote>
then I run:
</blockQuote>

<blockquote><pre>	cdrecord -scanbus
</pre></blockquote>
<blockQuote>
it says (sorry if hascii, Joerg has his name spelled properly here):
</blockQuote>

<blockquote><pre>Cdrecord 1.11a05 (i686-suse-linux) Copyright (C) 1995-2001 Jrg Schilling
Linux sg driver version: 3.1.22
Using libscg version 'schily-0.5'
scsibus0:
        0,0,0     0) 'SAF     ' 'CD-RW2224       ' '2.06' Removable CD-ROM
        0,1,0     1) *
        0,2,0     2) *
        0,3,0     3) *
        0,4,0     4) *
        0,5,0     5) *
        0,6,0     6) *
        0,7,0     7) *
</pre></blockquote>
<blockQuote>
And the drive becomes addressable as scd0, recordable <EM>in theory</EM> as sr0
but in practice I give the dev by host and lun number:
</blockQuote>

<blockquote><pre>	cdrecord dev=0,0 speed=4 some-random.iso
</pre></blockquote>
<blockQuote>
At least I hope speed 4 works, because it takes <EM>ages</EM> to make them at lesser
speeds.  I do have to wonder if something in my setup is slowing it all down
horribly, but hey, I'm not a big CD pressing house, I just wanna burn a CD
once in a while ... and that's what I get for having had a cd writer for so
long, the newer ones are faster.  
<IMG SRC="../../gx/dennis/smily.gif" ALT=":)" 
		height="24" width="20" align="middle">
</blockQuote>
<P><STRONG>
<IMG SRC="../../gx/dennis/qbub.gif" ALT="(?)"
	HEIGHT="28" WIDTH="50" BORDER="0"
	> 
Looking at that list again, maybe I've got too many modules involved.
Maybe I've got some sort of conflict?
</STRONG></P>
<P><STRONG>
I've changed the links in <TT>/dev:</TT>
</STRONG></P>

<pre><strong>lrwxrwxrwx 1 root root   9 May 29 21:39 /dev/cdrom0 -&gt; /dev/scd0
lrwxrwxrwx 1 root root   9 May 29 21:44 /dev/cdrom1 -&gt; /dev/scd1

 brw-rw----    1 root     disk      11,   0 Apr 11 07:25 /dev/scd0
 brw-rw----    1 root     disk      11,   1 Apr 11 07:25 /dev/scd1
</strong></pre>
<P><STRONG>
I've got the mount points defined in <TT>/mnt:</TT>
</STRONG></P>

<pre><strong> drwxr-xr-x    2 root     root        4096 May 12 04:39 cdrom
 drwxr-xr-x    2 root     root        4096 May 29 21:47 cdrom0
 dr-xr-xr-x    1 root     root        2048 Nov 20  1999 cdrom1
</strong></pre>
<P><STRONG>
but whenever I try to mount either of the cd-rom devices like so:
</STRONG></P>

<pre><strong> mount -t iso9660 /dev/scd0 /mnt/cdrom0
</strong></pre>
<P><STRONG>
or
</STRONG></P>

<pre><strong> mount -t iso9660 /dev/cdrom0 /mnt/cdrom0
</strong></pre>
<P><STRONG>
I get:
</STRONG></P>

<pre><strong>  mount: /dev/scd0 is not a valid block device
</strong></pre>
<P><STRONG><CODE>
also, "cdrecord -scanbus" doesn't seem to find anything.
</CODE></STRONG></P>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
	HEIGHT="28" WIDTH="50" BORDER="0"
	> [Heather] 
Then it's right, ide-scsi did not turn them into SCSI hosts.  ATAPI cdrom
support is being favored, and the IDE stuff doesn't directly lead to writing
under Linux.  (cdrecord doesn't speak ATAPI. It only speaks SCSI.)
</blockQuote>
<blockQuote>
Although in theory if your CD writer is really DVD capable too, you may be
able to write UDF filesystems to the disc (as hdc and hdd). I've never tried
that, and only UDF support on another machine would let them read the disc.
So it probably wouldn't be useful unless all your friends have DVD bays.
</blockQuote>
<P><STRONG>
<IMG SRC="../../gx/dennis/qbub.gif" ALT="(?)"
	HEIGHT="28" WIDTH="50" BORDER="0"
	> 
What am I doing wrong?  I'm sure it's probably something really stupid,
but I just can't see it.
</STRONG></P>
<P><STRONG>
A clue would be vastly appreciated.
</STRONG></P>
<P><STRONG>
adTHANKSvance!
</STRONG></P>
<P><STRONG>
Simeon
</STRONG></P>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
	HEIGHT="28" WIDTH="50" BORDER="0"
	> [Mike M.] 
this is seriously from memeory but try
</blockQuote>
<blockQuote>
first cat <TT>/proc/devices</TT> (I think)
</blockQuote>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
	HEIGHT="28" WIDTH="50" BORDER="0"
	> [Heather] 
It may be interesting to see this, but a fresh boot where you didn't try
to load the ide cdrom support would be more useful.  Approximately -
</blockQuote>

<blockQuote><ul>
<!-- *) You need the IDE interface itself, because that handles the IDE controller. -->

<LI>You need the IDE interface itself, because that handles the IDE controller.

<!-- *) You -probably- need IDE standard hard disk support for your main drives -->

<LI>You -probably- need IDE standard hard disk support for your main drives

<!--   so you can boot.  Unrelated to the cd bays, except for being on the IDE -->
  so you can boot.  Unrelated to the cd bays, except for being on the IDE

<!--   controllers too. -->
  controllers too.

<!-- *) You -do not- want IDE cdrom services. -->

<LI>You -do not- want IDE cdrom services.

<!-- *) IDE floppy services (those would be for LS-120 bays) or IDE tape services -->

<LI>IDE floppy services (those would be for LS-120 bays) or IDE tape services

<!--   have no effect either way on ATAPI CD-RW's. -->
  have no effect either way on ATAPI CD-RW's.

<!-- *) You -do- need ide-scsi, and from the scsi subsection you need sg (scsi -->

<LI>You -do- need ide-scsi, and from the scsi subsection you need sg (scsi

<!--   generic) support.  sg gets autoloaded when ide-scsi behaves correctly -->
  generic) support.  sg gets autoloaded when ide-scsi behaves correctly

<!--   and cdrecord is asked to scan the bus.  At least from my setup it doesn't -->
  and cdrecord is asked to scan the bus.  At least from my setup it doesn't

<!--   appear that SCSI-cdrom is used at all either. -->
  appear that SCSI-cdrom is used at all either.
</ul></blockQuote>

<blockquote><pre>-=: gemini :=- ~ # mount /dev/scd0 /mnt/cd
mount: block device /dev/scd0 is write-protected, mounting read-only
-=: gemini :=- ~ # lsmod
Module                  Size  Used by
sg                     28352   0  (autoclean)
ide-scsi                7312   1
</pre></blockquote>
<blockQuote>
(and a whole bunch of sound card modules.  working, as far as my dings and
talking-computer noises can tell 
<IMG SRC="../../gx/dennis/smily.gif" ALT=":D" 
		height="24" width="20" align="middle"> )
</blockQuote>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
	HEIGHT="28" WIDTH="50" BORDER="0"
	> [Mike M.] 
mount <TT>/dev/sd0</TT> <TT>/mnt/cdrom0</TT>
</blockQuote>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
	HEIGHT="28" WIDTH="50" BORDER="0"
	> [Heather] 
sd0 would be a scsi hard drive;  compact discs would be scd0 so after his
symlink the request is correct.  He just needs to untangle that mess of
modules.
</blockQuote>
<blockQuote>
For the record the system this is on is <A HREF="http://www.suse.com/">SuSE</A> 7.3, but I'm using a locally
built kernel - this answer is totally distro independent.
</blockQuote>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
	HEIGHT="28" WIDTH="50" BORDER="0"
	> [Mike M.] 
I remember I had to do a bit of fiddling around when I did it a while
ago
</blockQuote>
<P><STRONG>
<IMG SRC="../../gx/dennis/qbub.gif" ALT="(?)"
	HEIGHT="28" WIDTH="50" BORDER="0"
	> 
[sig block] If you're not outraged, you're not paying attention
</STRONG></P>
<blockQuote>
<IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
	HEIGHT="28" WIDTH="50" BORDER="0"
	> [Heather] 
Hmm, well tell your congressmen and representatives that supporting the
overly extended copyrights of MPAA and numerous corporations is against
the principle that the entire country is supposed to eventually benefit
from all of these works... great or otherwise... and a heavy infringement
on the right of individuals to make (and copy, and change, and redistribute)
works of our own invention.
</blockQuote>
<blockQuote>
(But, this isn't a politics thread.  Don't get me started.  If this bothers
you too go help the EFF, <A HREF="http://www.eff.org"
	>http://www.eff.org</A>.)
</blockQuote>

<!-- end 8 -->
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<H3 align="left"><img src="../../gx/dennis/qbubble.gif" 
	height="50" width="60" alt="(?) " border="0"
	>/dev/scd0 is not a valid block device?</H3>


<p><strong>From Simeon ben Nevel 
</strong></p> 
<p></strong></p>

<p align="right"><strong>Answered By  Mike Martin
</strong></p>
<P><STRONG><IMG SRC="../../gx/dennis/qbub.gif" ALT="(?)"
	HEIGHT="28" WIDTH="50" BORDER="0"
	>
Hmm,
</STRONG></P>

<pre><strong>&gt; &gt; options ide-cd ignore=hdb         # tell the ide-cd module to ignore hdb
</strong></pre>
<P><STRONG>
I thought the Grub/lilo incantation of hdc=ide-scsi &amp; hdd=ide-scsi
would take care of this?
</STRONG></P>

<pre><strong>&gt; &gt; alias scd0 sr_mod                    # load sr_mod upon access of scd0
</strong></pre>
<P><STRONG>
Would I also have to to "alias scd1 sr_mod" ?
</STRONG></P>
<P><STRONG>
I've read on several occasions that if you have 2 cd-rom devices on
the same ide interface, you really have to set them <EM>both</EM> up with the
ide-scsi modules.
</STRONG></P>

<pre><strong>&gt; &gt; pre-install sg     modprobe ide-scsi # load ide-scsi before sg
&gt; &gt; pre-install sr_mod modprobe ide-scsi # load ide-scsi before sr_mod
&gt; &gt; pre-install ide-scsi modprobe ide-cd # load ide-cd   before ide-scsi
</strong></pre>
<P><STRONG>
I did, indeed forget the modules.conf magic but I want to let you
know that my problem vanished when I rebooted my machine even without having
made the suggested changes.
</STRONG></P>
<blockQuote><IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
	HEIGHT="28" WIDTH="50" BORDER="0"
	> [Mike M.]
Out of curiousity - could you post the output of lsmod
</blockQuote>
<blockQuote>
I have a strong suspicion that on reboot the module loading was
corrected.
</blockQuote>
<blockQuote>
Just that if anyone searches for the same problem you had it is nice
to see the solution as well as the problem
</blockQuote>
<P><STRONG><IMG SRC="../../gx/dennis/qbub.gif" ALT="(?)"
	HEIGHT="28" WIDTH="50" BORDER="0"
	>
&lt;sigh&gt;
</STRONG></P>
<P><STRONG>
As much as I enjoy learning more about my linux system, it often
seems
that the solution to various problems involves magical spells of
one sort
or another.
</STRONG></P>
<P><STRONG>
Anyway, thanks again for taking the time to lend me a hand.
</STRONG></P>
<P><STRONG>
Sincerely,
</STRONG></P>
<P><STRONG>
Simeon ben Nevel
</STRONG></P>

<!-- end 8 -->
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