Thanks to James Courtier-Dutton and John Eayrs for their suggestions. For the
record (there is not much help on the web) the present situation is:
The following command used to write a disk image, generated by K3b, to a good
quality DVD+R using an ASUS 'DRW-1608P3S':
growisofs -dvd-compat -speed=4 -Z /dev/hdc=070113_Backup
This filed while writing the first block of data to disk. Th output contained
the following error lines:
:-( unable to TEST UNIT READY: Input/output error
:-? the LUN appears to be stuck writing LBA=310h, retry in 94ms
:-[ WRITE@LBA=c60h failed with SK=4h/ASC=08h/ACQ=03h]: Input/output error
:-( write failed: Input/output error
After this the DVD could be mounted. It had all the directories and some
complete files but most files were blank.
Hunting around the web, I found a pdf file containing the ATAPI error codes
(and a lot more) at:
ftp://ftp.avc-pioneer.com/Mtfuji_7/Spec/Fuji7r06.pdf
This shows that error 4/8/3 means "LOGICAL UNIT COMMUNICATION CRC ERROR
(ULTRA-DMA/32)". This points to the cable connection. However I also found
a discussion at:
http://readlist.com/lists/vger.kernel.org/linux-kernel/16/82588.html
From this and other comments I also concluded:
1. There may be a problem only affecting recent kernel versions.
2. There may be a problem associated with the ACPI system and DMA.
3. There may be a problem with the CPU disconnecting and connecting to the
bus when the CPU speed is changed due to load conditions.
Based on all this I bought a DVD Lens cleaner and used it, switched off DMA at
software and bios level, switched off cpu frequency changing at bios level
and after restarting the system, tried:
growisofs -speed=1 -Z /dev/hdc=070113_Backup
This worked right up to the time it tried to close the disk. The error
messages and last few lines are:
:-( unable to TEST UNIT READY: Input/output error
:-? the LUN appears to be stuck writing LBA=310h, retry in 141ms
....
3391389696/3414702080 (99.3%) @3.9x, remaining 0:04
3409674240/3414702080 (99.9%) @3.9x, remaining 0:00
builtin_dd: 1667344*2KB out @ average 3.8x1385KBps
/dev/hdc: flushing cache
/dev/hdc: closing track
/dev/hdc: closing session
:-[ CLOSE SESSION failed with SK=2h/ASC=04h/ACQ=07h]: Resource temporarily
unavailable
/dev/hdc: reloading tray
The last error message is wrong. 2/4/7 should read "LOGICAL UNIT NOT READY,
OPERATION IN PROGRESS" - so presumably it should have tried again after a
wait.
Unfortunately although 3.4 Gb had been successfully written, the DVD cannot be
mounted. The 'mount' command gives:
mount: block device /dev/hdc is write-protected, mounting read-only
mount: wrong fs type, bad option, bad superblock on /dev/hdc,
missing codepage or other error
Additionally 'dmesg' gives:
cdrom: This disc doesn't have any tracks I recognize!
attempt to access beyond end of device
hdc: rw=0, want=68, limit=4
isofs_fill_super: bread failed, dev=hdc, iso_blknum=16, block=16
So I will have to put DVD writing on hold until I have a better idea. One
question someone may be able to answer - is the superblock written last? If
so it might explain why the last disk cannot be mounted where the earlier
failed disk(s) can.
David Webb.
