Re: *nix data wipe tools

[wietse () porcupine org (Wietse Venema)]

David Cannings:
> Thomas C. Greene wrote:
> > I've posted the final versions of a few simple, free shell scripts that i've 
> > been working on to make data hygiene more convenient on *nix systems. Thanks 
> > to list members who helped test them and contributed improvements.
>
> Is there any specific advantage of these scripts over bcwipe?
>
> http://www.jetico.com/index.htm#/bcwipe_unix.htm

There's a general problem with applications that go through the
file system to destroy the contents of a file.  Unless one uses
very simplistic disk harware and file systems, there is no guarantee
that overwrite requests will actually overwrite the intended bits.
For a example, Solaris 10 ZFS uses copy-on-write, to avoid corruption
when the system crashes in the middle of an update; many disk drives
have write caches built-in so only the last overwrite request takes
effect; and non-volatile memory "disks" have a limited number of
write cycles and try to avoid hot spots.

        Wietse