According to Gilbert E. Detillieux:
According to Mel Seder:
My son-in-law is running Red Hat and 8.0 and he connected a CD RW drive.
What steps do I have to take to get the drive working in linux?
First, add the following line to the /etc/modules.conf file...
alias scsi_hostadapter ide-scsi
Then, you need to build an "initrd" file for your kernel, to load the ide-scsi driver automatically on system restart. Check your kernel version
...
Actually it doesn't need to be half that complicated. Since Red Hat 7.x, the installer automatically checks for a CD-RW drive, and if found, it will add the appropriate kernel boot command line option for enabling ide-scsi support, e.g. "hdc=ide-scsi". You can always add this manually after the fact, if the CD-RW drive is only installed later, but you need this kernel command line option whether you bother with the initrd stuff or not. In /etc/grub/grub.conf, you just add it to the kernel command line. If you use LILO, you have to add it via an append="hdc=ide-scsi" line in /etc/lilo.conf, and then rerun "lilo".
The initrd stuff isn't needed, though. All that's needed is for the /etc/rc.d/* files to do the necessary modprobes to load the ide-scsi drivers. Red Hat 7 & 8 do this with the following commands in rc.sysinit:
# If they asked for ide-scsi, load it if grep -q "ide-scsi" /proc/cmdline ; then modprobe ide-cd >/dev/null 2>&1 modprobe ide-scsi >/dev/null 2>&1 fi
For Red Hat 6, you can just add these to rc.local. The line in /etc/modules.conf is only needed if you make the initrd.
The other thing you may want to do is update the /dev/cdrom symlink so it points to the new device (usually scd0) rather than hdc or hdd:
ln -fs scd0 /dev/cdrom
If your system has both CD-ROM and CD-RW drives, it's just slightly more complicated. With the older 2.2 kernels, if ide-scsi remapped the CD-RW drive, it remapped the CD-ROM drive too, regardless of whether you indicated both drive mappings on the kernel command line. I don't know if that's still the case in 2.4, but I don't think it hurts to do that too. Generally the CD-RW should be the master (hdc) and will be mapped to scd0, while the CD-ROM as slave (hdd) will be mapped to scd1.