[Debburn-devel] DVD+RW format fails

[Thomas Schmitt]

Hi,

> I'm trying to solve an issue with formatting a DVD+RW medium.
> [...]
> Or generally, how to erase DVD+RW medium?

You do not have to erase DVD+RW in order to re-use them.
You can just overwrite the formatted area.

growisofs will warn about an existing ISO image on media and
wait a few seconds to give the opportunity to press Ctrl+C,
unless option -use-the-force-luke is given.

growisofs or libburn based programs will automatically re-start
formatting when they begin to write to a partially formatted DVD+RW.


If you want to make the stored data on a DVD+RW unreadable (*),
then overwrite it entirely by zero bytes:
  dd if=/dev/zero bs=1M count=4482 | \
   growisofs -use-the-force-luke -Z /dev/dvd=/dev/fd/0
or
  dd if=/dev/zero bs=1M count=4482 | \
   xorriso -as cdrecord dev=/dev/dvd -v -
which would also complete any partial formatting.

growisofs and xorriso will not clog your RAM with buffer data, as
would happen if you write via the Linux block device driver:
  dd if=/dev/zero bs=1M count=4482 of=/dev/sr0 

(*) Depending on the technical effort, overwritten data can be restored.
    For higher security: overwrite three times by random bytes.
    For highest security: physically destroy the media.


> If there are some data on the medium and I run:
> $ wodim -format formattype=force
> then it finishes without errors after 30s, but the medium isn't changed.
>
> But if I format the medium before using:
> $ dvd+rw-format /dev/dvd -force
> and then I run the same command:
> $ wodim -format formattype=force
> if will last approx. 20min. and seems to format the medium.
>
> I see no differences even in debug output.
>
> Does anybody know what can cause this difference?

DVD+RW normally get formatted in background while they are being
written. It is quite unusual to format them completely before writing
begins.

Background formatting is triggered by a FORMAT command that ends
quite quickly. Then the drive stays in formatting mode until the
media gets ejected or a CLOSE TRACK command arrives. Maybe the
second FORMAT command by wodim causes it to do a full formatting.
It depends much on the drive what it will do in such a situation.

Depending on the drive this command might do complete formatting:

  dvd+rw-format -lead-out /dev/dvd

Or with xorriso:

  xorriso -outdev /dev/dvd -format full


Have a nice day :)

Thomas