Re: Inquiry:How to totally wipe out the entire hard drive

[Napoleon <rri0187@attglobal.net>]

John Hasler wrote:
> I wrote:
> > If you want to destroy all the data for security purposes install and
> > use shred.  It will take quite a while on a large disk.
>
> Ron Johnson writes:
> > This really is a myth.
>
> What is?
>
> > So, just run "dd if=/dev/urandom of=..." over it a couple of times.
>
> man shred.  That's essentially what shred does, but it is probably
> faster then dd.  Note that you want to shred the device, not the files
> or partitions.
>
>
> In actual fact, overwriting with zeros once probably suffices for a
> modern drive (but there is the problem of bad blocks...)

(Should have gone to the list but I screwed up the first time - sorry).

Overwriting with zeros (or ones) once is not at all secure.  It can 
easily be nearly 100% recovered by someone with the necessary equipment, 
 even more so on a modern drive.

Overwriting multiple times with random data provides higher security. 
Physical destruction of the disk (i.e melting or physically shredding 
the disk) is the only sure-fire security.