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My CD-RW drive can read everything it writes

The HL-DT-ST CD-RW/DVD drive in my Lenovo T61 laptop, has a certain peculiarity. I was burning an ISO image, wich exceeded the supported size of a standard 80 minute CD by 7 MB. (The image was 707 MB.) Using cdrecord with the -overburn option seemed to work, until I tried to mount the CD-ROM. It would inevitably—

# mount /dev/cdrom /mnt/cdrom -t iso9660
mount: block device /dev/sr0 is write-protected, mounting read-only

Well, that is unexpected! I was going to write that it would refuse with some errors in dmesg about trying to access data beyond some boundary. But I probably messed up something very trivial, because I just can’t seem to reproduce the error in any way as the mount result above shows.

Let’s backtrack everything I did to try to fix this problem.

First, after numerous attempts to mount the 700 MB sized CD, I gave up and asked my little sister to bring me my stack of 800 MB CDs next time she’d come. Of course, over a week went by without her remembering to take the CDs. But eventually, I picked them up myself.

Having retrieved the 800 meg CDs, it came time to test them. Burning went well. Then mounting… A failure with dmesg showing the familiar error (which I now can’t look up because I can’t reproduce the problem 😛 ). Mounting it in the local server’s drive worked fine, though, leading me to think that my burner can’t read CD-ROMs it has written with overburn enabled.

Luckily, I was wrong. But I really don’t understand why I did get the errors at first. Sure, I did notice a faulty entry in my fstab, but I had also tried mounting it without relying on the fstab (i.e., with mount -t iso9660 /dev/cdrom /mnt/cdrom), which begot me the same error… Also, I had mounted plenty of CDs before this adventure.

All I can do to explain this is to concede that this is one of those problems where you usually call a geek friend telling them you can’t get something to work. They’ll reply by asking you have you tried this and that? Of course I have, at least twice, in the exact same sequence as you describe! Well, humour me then, and try it once more… Fuck! Fuck! Fuck! And why didn’t it work 10 minutes ago?! Don’t tell me you’ve never had this happen to you. Please?

In conclusion, after finding out that the 800 MB CD did work on my laptop, I reclaimed the 700 MB CD as well (which was now serving as a hawk-deflector in the coop) to find out that, even after being exposed to lots of rain and sun for over a week, this CD also mounted without hesitation.


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