Re: cdrskin: formatting blank=format_defectmgt: % is jumpy (DVD-RAM)

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

> Linux RHEL5 in a VMware VM, using host's SATA burner
> cdrskin --allow_setuid dev=$cddev -v blank=format_defectmgt
>         1%   78%   40%  ..  2%   22%   98%    ...   3% .... 100%

libburn inquires these numbers from the drive, which is a virtual device
here, i assume, with SCSI passthrough to the real drive.

(Off topic:
 Was there any difficulty to get this setup working ? I did a similar
 test with Debian on qemu on Debian recently and it was not really easy.
 Do host system and guest system properly recognize media changes and
 changed sizes due to burn runs ?)


> If I use
>         dvd+rw-format -force=full /dev/cdrom
> the % increases monotonically (1% ... 3% ... 50 % ..... 100%)

My first theory was that growisofs would not accept backward jumps.
But it does not look like that in the source code (transport.hxx :
wait_for_unit() : variable *progress).

So i would need the log of the conversation between cdrskin and the drive.
You get it by option -V (capital v) and it will be lenghty. So catch its
output in a file. E.g.:

  cdrskin --allow_setuid dev=$cddev -v blank=format_defectmgt \
          -V 2>&1 | tee -i /tmp/cdrskin.log

The formatting procedure is initiated by an SCSI command FORMAT UNIT,
which should report preliminary success after a short time.
Then the drive gets asked periodically whether it is ready.
The not-ready replies contain the progress indicating numbers between
0 and 65535.


It might also be interesting to catch all messages from dvd+rw-format
in another log file. Just in case that it displays wrong percentages
for very short time spans.


Have a nice day :)

Thomas