On 7/31/07, Thomas Schmitt <[EMAIL PROTECTED]> wrote: > Hi, > > > 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 > > ... > > :-[ [EMAIL PROTECTED] 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 > > On occasion of anniversary of libburn revival let me state > that the equivalent cdrskin commands would be > cdrskin -v dev=/dev/hdc blank=deformat_sequential > resp. > cdrskin -v dev=/dev/hdc blank=format_overwrite > > Blanking but not formatting can be done with cdrecord and wodim > cdrecord -v dev=ATA:1,0,0 blank=all > wodim -v dev=/dev/hdc blank=all > If you use blank=fast then the media will not be useable for > /dev/zero as data source unless you specify an image size. > (I never tried growisofs -use-the-force-luke=tracksize:<number>) > > > > 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. > > You seem to expect the media to behave like DVD+RW. > So format it once. > dvd+rw-format /dev/hdc > -force should not be needed because it is not formatted. > But i never tried without -force. > > > > 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) > > 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. > > 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. > > For repeated backups i only use 4x DVD+RW. > They get formatted automatically and blanking is not > applicable to them. > > > Have a nice day :) > > Thomas
Wow - that's a lot of information. I can now see that my understanding (i.e. dvd-rw and dvd+rw were the same) was very wrong! Thomas, thank you for the info - I really appreciate it. I don't understand it all now, but I will read it (10 times) and try to understand this "mode"/"recording strategy" thing better. (I've also just found http://fy.chalmers.se/~appro/linux/DVD+RW/-RW/ which explains the same subject, I think) Jaime :-) -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
