/dev/cdrom : can't read superblock

[Charles Trois]

Here is my problem: the cdrom drive of my LCD iMac used to work perfectly,
but it doesn't any more.

What happens is that I am unable to open it:

[root@sirrah mnt]# eject
eject: unable to open `/dev/cdrom'

Seeing that the device was not mounted, I tried to do it:

[root@sirrah mnt]# mount /dev/cdrom /mnt/cdrom
mount: /dev/cdrom: can't read superblock

I also tried this test, which failed:

[root@sirrah mnt]# cat /dev/cdrom | od | more
cat: /dev/cdrom: Input/output error
0000000

The kernel is 2.4.22 and includes all the necessary support; moreover, it is
aware of the device:

hdb: HL-DT-ST RW/DVD GCC-4120B, ATAPI CD/DVD-ROM drive

The device is listed on /etc/fstab.

I would add that the trouble does not depend on whether there is a disc in
the drive or not, and that this works normally under MacOS.

The basic question seems to be that of the "superblock": where is it, what
is in it, why could it not be read?

I have made a Google search on the Web, I have read the various howtos and
the doc files in the source directory, but I have found nothing quite to the
point.

Would someone have a better idea?

Thanks in advance.

Charles