Re: readahead logic and I/O errors

[Michael Tokarev <mjt@tls.msk.ru>]

linux-os (Dick Johnson) wrote:
> On Wed, 15 Feb 2006, Michael Tokarev wrote:
> 
> 
>>The thing is: I just fired a cdrom drive in my PC.
>>It was a good device, and now it's dead.
>>And the reason is the readahead logic, plus an unreadable
>>(damaged, scratched) CD-rom.
[]
> Aside from the obvious read-ahead bug you discovered, have you
> tried your CD drive after the reboot? It is not possible to
> kill those things with software, even if attempting to write
> with too much infrared LED drive. There is nothing except for
> the removable disc to get hurt. Even the "head" isn't in contact.
> It's just some infrared light, focused with a voice-coil, that
> moves on a fixed platform.

I opened the drive after BIOS didn't detect it on reboot (after
power-off).  There's one fired (burned? perished? how's that in
english?) chip on the plate, wich smells like fired silicone.
  It looks like a ~5mm pit in the center of square chip, full of
ache, and there's a crack across it.  The drive is dead.

I think it's a chip which controls one of the motors of the drive,
most probably the one which moves the head, because the head
motor connector is right near the chip.

When I turned off power, the drive was *hot*, and it started
"trembling" (or chattering) when I turned power off.

It was a dvd-cd combo (read dvd, read-write cd) Teac drive, I
don't remember the model (there's no label on the drive, and
I can't send inquiry/identify command to it anymore, obviously).

Yest it looks like a problem in the drive *too*, as it should
not behave like that in the first place.  But the thing is, I
did know something's bad going on, I saw it, but I wasn't able
to stop it from linux, only poweroff stopped things from going.

/mjt