[Bug 501667] Re: -force invalid command line option

[Stuart R Balfour]

I think I see what's going on.  I scrounged the dvd+rw-format source for
warnings and errors uniquely associated with -force=full, found exactly one, and
was able to reproduce it.  The media was virgin DVD+RW (or DVD+RW DL).
The command was:

> /usr/bin/dvd+rw-format -force=full /dev/sr1

* BD/DVD±RW/-RAM format utility by <appro at fy.chalmers.se>, version 7.1.
* 4.7GB DVD+RW media detected.
- unimplemented command-line option for this media.
- you have the option to re-run /usr/bin/dvd+rw-format with:
  -lead-out  to elicit lead-out relocation for better
             DVD-ROM compatibility, data is not affected;
  -force     to enforce new format (not recommended)
             and wipe the data.                                             

Full formatting DVD+RW media is not implemented because it is not necessary:
formatting information is written incrementally, concurrently with data.  Normally
formatting happens automatically when the burn process starts.  While it would
be possible to fully format DVD+RW media before any data writing, it would not
provide any additional functionality.  Furthermore, reformatting severely degrades
the rewritability of the media.  You may be able to reformat quality media perhaps
10 times, and poor media only a handful of times before it becomes effectively
read-only media.  For data writing, the media is rewritable in excess of 1000
times.

If you are attempting to reformat the media to erase data, writing the format 
information will NOT zero the data - it still exists and can be recovered with
forensic tools.  If you want to erase the data, you must 'blank' the media:
dvd+rw-format -blank <device> (or you can simply overwrite the data with
new data in the usual way).

If you have an example of how full formatting of DVD+RW provides useful 
functionality sufficient to offset the degradation in rewritability, you might
convince a developer to implement it.  We aim to please :-)
                                                                                -Stuart

** Changed in: dvd+rw-tools (Ubuntu)
       Status: New => Confirmed

** Changed in: dvd+rw-tools (Ubuntu)
     Assignee: (unassigned) => Stuart R Balfour (sbalfour)

-- 
-force invalid command line option
https://bugs.launchpad.net/bugs/501667
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