Re: How to "blank" / "zero out" / "nullify" a dvd-rw?
"Thomas Schmitt" <email@example.com> wrote:
> > I'm trying to "blank" / "zero out" / "nullify" a dvd-rw that has
> > previously had data written to it, so that I can give that dvd-rw to
> > someone else and they wont see the data. (NB I'm _not_ worried about
> > "magnetic/optical history", the FBI, the CIA etc).
> > Please note that I DO NOT necessarily want to turn the disk back to
> > the way it was when it was still in its plastic wrapper.
> > ...
> > ~# growisofs -Z /dev/hdc=/dev/zero
> > ...
> > :-[ WRITE@LBA=0h failed with SK=5h/ASC=30h/ACQ=05h]: Wrong medium type
> > :-( media is not formatted or unsupported.
> > :-( write failed: Wrong medium type
> > ...
> > ~$ dvd+rw-mediainfo
> > ...
> > Mounted Media: 14h, DVD-RW Sequential
> You got a sequentially written DVD-RW.
> Before you can overwrite its content it needs to be blanked
> dvd+rw-format -blank=full /dev/hdc
> or formatted
> dvd+rw-format -force /dev/hdc
If the media was written in the default (reliable) sequential
mode, you only need to call cdrecord blank=fast
A full blank is only needed if the media was written in packet mode
before or if it was formatted.
> On occasion of anniversary of libburn revival let me state
Well, cdrecord will soon have it's 10th DVD writing anniversary ;-)
> Blanking but not formatting can be done with cdrecord and wodim
> cdrecord -v dev=ATA:1,0,0 blank=all
This is not needed.....
cdrecord usually works without dev= parameter. If you need it because
you have more than one drive, dev=ATA:1,0,0 will not work.
Then you should call cdrecord -scanbus and the most possible
parameter is dev=1000,0,0
> wodim -v dev=/dev/hdc blank=all
Let me not comment non-free software...
> > But (and this is the strange part), if I format the disk using
> > "dvd+rw-format -blank=full /dev/hdc" (which works), then "growisofs -Z
> > /dev/hdc=/dev/zero" works perfectly THE FIRST TIME - it only fails the
> > second time I try to do it.
> That's because unformatted DVD-RW are much like CD-RW.
> You can write a session to them, leave them open, append
> another session, and so on. But you can re-use them only
> after blanking.
> dvd+rw-format -blank=full brings a DVD-RW into this
> unformatted state. -blank without "=full" does the same as
> cdrecord blank=fast.
It is most unlikely that dvd+rw-format -blank=full does the same
as cdrecord blank=fast. This would be counter-intuitive.
> > is there a way to "blank" / "zero out" / "nullify"
> > a dvd-rw which won't permanently destroy the
> > disk if I do it 20 times?
> (start sarkasm) To my experience, most DVD-RW are destroyed
> before they get into their shrink wrap. (end sarkasm)
DVD-RWs last a very long time if you use the right software, e.g. cdrecord.
> Formatting is needed only once. The media stays overwriteable
> until you deformat it or it finally refuses to work with
> your drive. So there is no problem with 20 times or so.
Formatting DVD-RWs will take them into a less reliable mode.
> Blanking (i.e. deformatting) seems not to be more dangerous
> to the media than overwriting with data. This way or that
> way the media will give up its life early enough.
> I got 3 DVD burners and none of them works well with 4x DVD-RW.
DVD-RWs are very reliable. DVD+RW is a mess, I found no drive that
realiably reads DVD+RWs written by drives from another brand.
Be sure to prefer cdrecord blank=fast over cdrecord blank=all
EMail:firstname.lastname@example.org (home) Jörg Schilling D-13353 Berlin
email@example.com (work) Blog: http://schily.blogspot.com/
URL: http://cdrecord.berlios.de/old/private/ ftp://ftp.berlios.de/pub/schily