What happened to DVD writing?

[Warren Block]

On Sun, 20 Sep 2009, Zaphod Beeblebrox wrote:
>>
>> FreeBSD lightning 7.2-STABLE FreeBSD 7.2-STABLE #0: Sun Sep 20 07:25:58 MDT
>> 2009      root at lightning:/usr/obj/usr/src/sys/LIGHTNING  i386
>>
>> Now growisofs starts, but appears to never manage to write to the DVD. It's
>> a DVD-R, one from the same batch that has worked before:
>>
>>  0.77% done, estimate finish Sun Sep 20 07:55:57 2009
>>
>> and there it stops.  Rebooting is needed, and the machine can't quite bring
>> itself to shut down after syncing buffers.  /var/log/messages:
>>
>> Sep 20 07:42:44 lightning kernel: acd0: FAILURE - READ_BUFFER ILLEGAL
>> REQUEST as c=0x24 ascq=0x00
>> Sep 20 07:42:46 lightning kernel: acd0: FAILURE - MODE_SELECT_BIG ILLEGAL
>> REQUEST asc=0x24 ascq=0x00
>> Sep 20 07:42:56 lightning kernel: acd0: FAILURE - READ_TOC ILLEGAL REQUEST
>> asc=0x24 ascq=0x00
>> Sep 20 07:43:25 lightning kernel: acd0: WARNING - TEST_UNIT_READY taskqueue
>> time out - completing request directly
>> Sep 20 07:43:36 lightning kernel: acd0: WARNING - TEST_UNIT_READY freeing
>> taskqueue zombie request
>> Sep 20 07:45:26 lightning kernel: acd0: WARNING - PREVENT_ALLOW taskqueue
>> timeout - completing request directly
>> Sep 20 07:45:26 lightning kernel: acd0: WARNING - PREVENT_ALLOW freeing
>> taskqueue zombie request
>>
> I recently upgraded from 7.0 to 7.2-p3.  I just last night cut a dual layer
> DVD with growisofs.  It appears to have cut fine.
>
> When growisofs stops in the middle like that, it's often caused by media
> defects.  Have you tried another disk?

Yes, same effect.  Also with a DVD+R.  Also tried it on 8-STABLE, same 
messages, same results.

> Another possibility is that the drive is worn out.  DVD writers have a
> limited lifespan largely measured by the number of disks they cut.

This drive has probably written under 50 DVDs, all ISOs used for backup. 
It's a Lite-On DH-20A4P bought in August 2008.  It's looking like the 
drive itself has failed.  Which seems odd, since I thought it could 
still burn CDs.

-Warren Block * Rapid City, South Dakota USA