OT: Can Reformatting A Hard Drive To ext3 Destroy All the Data On It?

[Bruno Wolff III]

On Fri, May 29, 2009 at 21:51:57 +0200,
  Srdan Tosovic <tos at prip.tuwien.ac.at> wrote:
> 
> as root will write various bit patterns 25 times over the entire drive
> (see the man page for more options).

If recovery after one pass of rewriting a disk is a credible threat you
should be physically destroying the disks. Writing over the disk multiple
times is not going to reach some sectors (bad ones or spares) and for most
people the threat of using an electron microscope to try to overwritten data
is not a credible threat. So there isn't a lot of point of doming anything
more than writing zeros over the disk, after the fact. Using block level
encryption in the first place is a relatively cheap way to make recovery
harder as well as protect against some other things.