After a few weeks using the auxiliary battery instead of the CD-ROM drive, I needed to read a DVD. Surprise! It didn’t work. Reboot. Still no luck.
dmesg didn’t show anything about IDE, and /proc/ide was empty. It was like the CD-ROM didn’t exists at all.
The explanation might be that the CD-ROM is a SATA drive, not PATA. Graham William’s GNU/Linux Desktop Survival Guide holds the key to enable the drive. In short:
# cp /boot/initrd.img-`uname -r` /boot/initrd.img-`uname -r`.bak
# mkinitrd -o /boot/initrd.img-`uname -r`
(Part of the ongoing Debian GNU/Linux on Dell D620 saga.
[tags]Dell, D620, SATA, cdrom[/tags]