Re: Wiping a disk clean

[bdbryant@mail.utexas.edu (Bobby D. Bryant)]

On Tue, 02 Aug 2005, Larry Hazel <lhhazel@otelco.net> wrote:

> If I create a binary file, use sequential_io to write records of all 
> ones until Use_Error is raised.  Then, delete the file and repeat with 
> all zeros.
> Will the unused portion of the disk be wiped clean so that no one could 
> recover what was written there before?

Modulo the caveats a couple of others have already mentioned re
partially used allocation units, it would be easier and probably more
effective to repeat

	$ cat /dev/random > temp.dat ; rm temp.dat

a few dozen times.

As I understand it, the need for repetition comes from the fact that
a drive wobbles somewhat during use, so whenever you overwrite a
sector it may leave a "fringe" of the earlier data to one side or the
other of a track.

-- 
Bobby Bryant
Austin, Texas