How can I overwrite every sector on a CD-RW?

Ingo

New Member
I have a notebook that is used with Windows XP or with Windows 9x.

With the mentioned operating systems I want to have the ability to overwrite every sector on a CD-RW. As far as I know, all data of a medium is overwritten if every sector of the medium was overwritten.

The FAQ of Eraser contains the following sentence:
"You can use Eraser on a CD-RW, however you only need to use one pass, as only magnetic media needs multiple passes."

But since Eraser and "Darik's Boot and Nuke" can definitively not be used to peform an overwrite of EVERY sector of a Medium, I wonder how to do it.

Some utilities like KillDisk overwrite EVERY sector of a medium. But they seem not to support CD-RW's.

Some Software to burn CD's like nero can delete a whole CD-RW.
But is all data of the CD-RW overwritten by that way?

Any help will be appreciated.
 

Gralfus

Member
The best way to know this is to try it and test the results. Create an image of the media using "dd" or another forensic imaging program, then examine the image in a hex editor. If you chose to overwrite with zeros, then all you should see are zeros. If you overwrite with psuedorandom data, then you won't be able to tell if it was overwritten, because each byte is random. I have yet to try DBAN or Eraser on a CDRW, but this is how I will test it when I do try them.
 

Glenn

Member
Ingo said:
... But since Eraser and "Darik's Boot and Nuke" can definitively not be used to peform an overwrite of EVERY sector of a Medium, I wonder how to do it. ...
Just curious why you say that.

In any case, given the low price of media, is there a reason you don't just physically destroy the disks?
 

Ingo

New Member
Glenn said:
Ingo said:
... But since Eraser and "Darik's Boot and Nuke" can definitively not be used to peform an overwrite of EVERY sector of a Medium, I wonder how to do it. ...
Just curious why you say that.

In any case, given the low price of media, is there a reason you don't just physically destroy the disks?
As far as I remember, I read somewhere on the internet, how DBAN does work. But I can not find this place anymore. The only thing I remembered is that DBAN does not overwrite every sector of the medium to wipe. But a utility that overwrites EVERY sector of a medium would also wipe remapped sectors. But DBAN does not as you can read at
http://dban.sourceforge.net/faq/index.html#hardware.

Also DBAN seems not to support writing to CD's anyway.

By reading the topic "What Does It Do: When Erasing Unused Disk Space" of the "Eraser Help" you can find that Eraser obviously does not write to the disk on sector level. So you can expect that eraser will not overwrite EVERY sector of the disk even if its filetree has previously been deleted completely. Most notably the free space in sectors of the filesystem like FAT sectors may not be completely overwritten by eraser.
On CD-RW's I expect a problem similar to that described above.


If you ask why not to destroy disks instead of to overwrite and reuse them, you can also ask why there are CD-RW's. If you physically destroy CD's instead of to overwrite them, you will only need CD-R's.
E.g. if you want to write data to a CD and erase it automatically later, you can not do this by physically destroy the CD because the computer has not the ability to do so.
 

Glenn

Member
I agree that DBAN isn't suited for removable media but why not Eraser?

If you format the CD-RW to wipe the file allocation table, then Erase unused space, why wouldn't it ovewrite all sectors? (This assumes you have some form of drive letter access/small packet writing utility for your burner.)

The problem of course is that, technically, laser misalignment can result in some remaining traces of the previous burns (a problem only if you expect a forensic examination by experts).

I agree that RW media are for rewriting but, if you were willing to burn the data to the media in the first place, why are you worried about it now? I had assumed you were concerned about final disposal of the media, e.g, obsolete data, or medium becoming unreliable.
 
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