Trouble with SCSI emulation for DVD/CDRW drive
 

Hi, I have read and tried to get my second CDROM drive recognized using scsi emulation, so i may burn CD's. I use Redhat 9. I believe my kernel (2.4.20-8smp) has scsi emulation enabled. Here's what i have done.

In /etc/grub.conf added to line to create:

kernel /vmlinuz-2.4.20-8smp ro root=LABEL=/ apic acpi=off hdd=ide-scsi

In my /etc/fstab:

LABEL=/ / ext3 defaults 1 1
LABEL=/boot /boot ext3 defaults,nodev 1 2
LABEL=/space /space ext3 defaults,nodev 1 1
none /dev/pts devpts gid=5,mode=620 0 0
none /proc proc defaults 0 0
none /dev/shm tmpfs defaults 0 0
/dev/hda6 swap swap defaults 0 0
/dev/cdrom /mnt/cdrom udf,iso9660 noauto,owner,kudzu,ro,nosuid,nodev 0 0
/dev/cdrom1 /mnt/cdrom1 udf,iso9660 noauto,owner,kudzu,nosuid,nodev 0 0
/dev/fd0 /mnt/floppy auto noauto,owner,kudzu,nosuid,nodev 0 0


In my /dev directory, the result of "ls -l cdrom*" is"

lrwxrwxrwx 1 root root 3 Nov 13 14:24 cdrom -> hdc
lrwxrwxrwx 1 root root 4 Nov 13 15:08 cdrom1 -> scd0

and in my /mnt directory:

total 12
drwx------ 2 root root 4096 Nov 13 14:24 cdrom
drwx------ 2 root root 4096 Nov 13 14:24 cdrom1
drwxr-xr-x 2 root root 4096 Oct 24 09:15 floppy

Now looking at the link in /dev for cdrom1 (my DVD/CDRW is cdrom1) it seems it IS loaded using scsi emulation. But in my boot messages:

ide1: BM-DMA at 0xffa8-0xffaf, BIOS settings: hdc:DMA, hdd:DMA
hdd: SAMSUNG CDRW/DVD SM-348B, ATAPI CD/DVD-ROM drive
hdd: DMA disabled

it says it's ATAPI, and when i run XCD-Roast, it too tells me that if I used scsi emulation, things would work better, as my versionof XCD -Roast supports ATAPI devices but not well. And XCD-Roast can't even see that I have a CD in the drive, it keeps asking for one, when one is in there. What the heck is going on here?

What is the output of:
cdrecord --scanbus

Okay it sees it finally. I DO get output from cdrecord -scanbus. Phew.

But now I have to tackle the problem of it mounting the CDRW/DVD drive in read-only, as I still can't write to it.

# mount /mnt/cdrom1
mount: block device /dev/cdrom1 is write-protected, mounting read-only

# ls -l /dev/cdrom1
lrwxrwxrwx 1 root root 4 Nov 15:08 /dev/cdrom -> scd0

# ls -l /dev/scd0
brw-rw---- 1 root disk 11, 0 Jan 30 2003 /dev/scd0

Looks like it's rw to me. At least for root, and that's who I'm working as.

cdrecord actually uses the real device ID for writing and does not care about any option in the fstab file. You do not mount a CD prior to burning and so writing to CDRWs is the same process as writing to CDRs. The 2.6 kernel is supposed to fully support UDF i..e packet writing like Roxio DirectCD and Nero's InCD.

I can't write using this drive!!!! Screen dump of my tries:

# cdrecord -v speed=24 dev=0,0,0 -data /root/yarrow-i386-disc1.iso
Cdrecord 2.0 (i686-pc-linux-gnu) Copyright (C) 1995-2002 J?rg Schilling
TOC Type: 1 = CD-ROM
scsidev: '0,0,0'
scsibus: 0 target: 0 lun: 0
Linux sg driver version: 3.1.24
Using libscg version 'schily-0.7'
atapi: 1
Device type : Removable CD-ROM
Version : 0
Response Format: 1
Vendor_info : 'SAMSUNG '
Identifikation : 'CDRW/DVD SM-348B'
Revision : 'T503'
Device seems to be: Generic mmc2 DVD-ROM.
Using generic SCSI-3/mmc CD-R driver (mmc_cdr).
Driver flags : MMC-3 SWABAUDIO BURNFREE
Supported modes:
Drive buf size : 1959936 = 1914 KB
FIFO size : 4194304 = 4096 KB
cdrecord: Drive does not support TAO recording.
cdrecord: Illegal write mode for this drive.

# cdrecord -v -dao speed=24 dev=0,0,0 -data /root/yarrow-i386-disc1.iso
Cdrecord 2.0 (i686-pc-linux-gnu) Copyright (C) 1995-2002 J?rg Schilling
TOC Type: 1 = CD-ROM
scsidev: '0,0,0'
scsibus: 0 target: 0 lun: 0
Linux sg driver version: 3.1.24
Using libscg version 'schily-0.7'
atapi: 1
Device type : Removable CD-ROM
Version : 0
Response Format: 1
Vendor_info : 'SAMSUNG '
Identifikation : 'CDRW/DVD SM-348B'
Revision : 'T503'
Device seems to be: Generic mmc2 DVD-ROM.
Using generic SCSI-3/mmc CD-R driver (mmc_cdr).
Driver flags : MMC-3 SWABAUDIO BURNFREE
Supported modes:
Drive buf size : 1959936 = 1914 KB
FIFO size : 4194304 = 4096 KB
cdrecord: Drive does not support SAO recording.
cdrecord: Illegal write mode for this drive.
[root@thunder etc]#

So, apparently I can't write using DAO or SAO or TAO. What the heck is going on here?

Maybe you will have to edit your lilo.conf file so the drive is detected first as a scsi device, not an ide device. Try adding something like this line to your lilo.conf file.


append=" hdc=ide-scsi devfs=mount quiet "

Just a guess, really. Good luck!