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Date: Fri, 29 Oct 2010 12:00:17 +0100
From: Bruce Cran <bruce@cran.org.uk>
To: Garrett Cooper <gcooper@FreeBSD.org>
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Cc: Doug Barton <dougb@freebsd.org>, d@delphij.net,
	Ulrich =?ISO-8859-1?Q?Sp=F6rlein?= <uqs@spoerlein.net>,
	Gary Jennejohn <gljennjohn@googlemail.com>,
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	Bruce Evans <brde@optusnet.com.au>, svn-src-head@freebsd.org,
	Alexander Best <arundel@freebsd.org>, svn-src-all@freebsd.org,
	Dag-Erling Smorgrav <des@freebsd.org>
Subject: Re: svn commit: r214431 - head/bin/rm
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On Thu, 28 Oct 2010 14:11:14 -0700
Garrett Cooper <gcooper@FreeBSD.org> wrote:

> Unfortunately it's implied superficially by the 3 pass tort; but as
> most people who understand magnetic disks know, unless you completely
> obliterate a disk, wipe over it with random data enough times,
> whatever, the content is still on the disk and retrievable via various
> methods... I agree that this advice should be placed near the flag
> itself so that people completely understand the implications of the
> feature.

I believe the only method 10-15 years ago would have been a scanning
electron microscope, but that probably isn't possible with today's
disks. Simply writing zeros once is enough to obliterate all the data
(except for any remapped sectors).

-- 
Bruce Cran