<html dir="ltr"><head></head><body style="text-align:left; direction:ltr;"><div>Really? The only groups that want the data _that_bad_ have subpeonas. The other groups that can read around the holes already have your data. All you're really trying to do is make sure the drive is not usable for the basic computer bad guy.</div><div><br></div><div>As areal densities have increased exponentially from 10M drives to 10TB drives in the same space, the size, and thus strength, of the magnetic domains has decreased exponentially. So the bleed over has also decreased. The transition to vertical magnetic domains has made the crosstalk to the platter substrate nearly zero. Add in the platters are simply not magnetizable at all and there's basically no data bits anywhere possible except on the platter surface.</div><div><br></div><div>bad ascii art:</div><div><br></div><div>N-S bit domain on surface</div><div>___ platter surface</div><div><br></div><div>S-N induced bit domain subsurface</div><div><br></div><div> N S</div><div> | | 2 adjacent vertical domains 1 0</div><div> S N</div><div>____ platter surface</div><div><br></div><div> N - S Induced data bits are just wrong! Now mix in the 2D spacial arrangement and which subsurface pole pairs with which other? No monopoles in magnetic media (yet :-)</div><div><br></div><div><br></div><div><br></div><div>On Thu, 2019-04-11 at 13:31 -0700, Alex Carver via Ale wrote:</div><blockquote type="cite" style="margin:0 0 0 .8ex; border-left:2px #729fcf solid;padding-left:1ex"><pre>If someone really wants your data, holes don't matter. The rest of the</pre><pre>platter is still intact in that case and can have the data extracted.</pre><pre><br></pre><pre>There's also no guarantee that Dban can write enough to be sure that the</pre><pre>magnetic domains are fully randomized deep in the platter. The longer</pre><pre>data sits statically on the disk the more opportunity for the surface</pre><pre>domain to imprint on deeper domains (this is actually a problem with</pre><pre>magnetic tape, magnetic data can print through from one layer of tape to</pre><pre>the next layer when it's wound on the spindle).</pre><pre><br></pre><pre>A serious entity can perform a deep level scan of the platter and</pre><pre>retrieve the low level signal under the surface domains and see previous</pre><pre>data. The drive head typically isn't powerful enough to write that</pre><pre>deeply because it has to keep the tracks narrow.</pre><pre><br></pre><pre>On 2019-04-11 12:13, Steve Litt via Ale wrote:</pre><blockquote type="cite" style="margin:0 0 0 .8ex; border-left:2px #729fcf solid;padding-left:1ex"><pre>On Wed, 10 Apr 2019 22:11:42 -0400</pre><pre>Jim Kinney <</pre><a href="mailto:jim.kinney@gmail.com"><pre>jim.kinney@gmail.com</pre></a><pre>> wrote:</pre><pre><br></pre><blockquote type="cite" style="margin:0 0 0 .8ex; border-left:2px #729fcf solid;padding-left:1ex"><pre>Dban advantage: it can be done across hundreds or thousands of drives</pre><pre>before larcenous third party "shredders" physically touch the drives.</pre></blockquote><pre><br></pre><pre>That's a good point.</pre><pre><br></pre><pre>Doesn't dban take an hour or more? How many drives can I do with one</pre><pre>computer? How long would it take to test whether each is really blank?</pre><pre><br></pre><pre>What might be nice with 1000 drives to do is dban followed by drilling</pre><pre>3 holes in each drive. I'd say each drive would take 1 minute for 3</pre><pre>holes, so it's about 2 days for one employee to drill the holes. Or,</pre><pre>perhaps, one employee could both dban and drill the holes, drilling the</pre><pre>holes while the next batch is dbanning.</pre></blockquote><pre>_______________________________________________</pre><pre>Ale mailing list</pre><a href="mailto:Ale@ale.org"><pre>Ale@ale.org</pre></a><pre><br></pre><a href="https://mail.ale.org/mailman/listinfo/ale"><pre>https://mail.ale.org/mailman/listinfo/ale</pre></a><pre><br></pre><pre>See JOBS, ANNOUNCE and SCHOOLS lists at</pre><a href="http://mail.ale.org/mailman/listinfo"><pre>http://mail.ale.org/mailman/listinfo</pre></a><pre><br></pre></blockquote><div><span><pre><pre>-- <br></pre>James P. Kinney III
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