Re: Writing Dual Layer DVD-RW using Linux

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

Hi,

> So if I want to overwrite an old back-up on the DVD with a new back-up,
> I would just use the above command?  I won't need to format the DVD
> again?

If it is a formatted media then it can be overwritten
without any further blanking or formatting.
DVD-RAM are sold formatted, DVD+RW get formatted by
the burn programs automatically on first use.

DVD-RW are sold unformatted and can be used in that
state. Unformatted DVD-RW need to be blanked before re-usal:
  dvd+rw-format -blank=full /dev/hdc

DVD-RW can be formatted to behave much like DVD+RW or DVD-RAM:
  dvd+rw-format -force /dev/hdc

This formatting has to be done only once per media
unless it gets revoked by a blanking command.


> I don't know why reformatting does this in comparison
> to "blanking it" (however that is done). Aren't reformatting and
> blanking effectively the same?

Formatting and blanking are antagonists.

Formatting allows random write access with a restriction
to alignment of addresses and data amounts (multiples of 2K
with DVD-RAM, DVD+RW, multiples of 32K with DVD-RW).

Blanking means to invalidate formatting and/or payload data.
Media are to be written sequentially afterwards.

Wether formatting really does more harm than writing
is hard to judge. You only know for sure that the media
is dead - not why it died.


> I would need to go to HD-DVD or Blu-Ray...

growisofs promises to do BD-RE.

Hey, if you got such a drive - would you be tester
for my program cdrskin ?
It still waits for a wealthy user with such hardware
(or a spindle full of DVD DL).


Have a nice day :)

Thomas