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<div class="moz-cite-prefix">On 27/06/13 11:01, Omer Zak wrote:<br>
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<br>
<blockquote cite="mid:1372320082.6153.103.camel@c4" type="cite">
<pre wrap="">
Does anyone know where to buy (or how to make) a Faraday cage suitable
for protecting a hard disk against EMP from an A-bomb exploding at
distance of say 10Km?</pre>
</blockquote>
This info is from memory, so verify or trust at your own risk.<br>
<br>
The US military once activated an A-bomb at a considerable height
over the pacific ocean. This caused street lights in Hawai, <b>900
miles away</b>, to blow out. In fact, that how we know of EMP in
the first place.<br>
<br>
The second piece of input I do not remember who told me. A
University was doing experiments with EMP by quickly discharging a
very very very big capacitor (and I'm referring to both capacity and
actual size). They were doing this inside an underground shelter
that had 1 meter thick led walls. Computers on the other side of the
wall would occasionally fry.<br>
<br>
At 10km, your hard disk is most likely to be completely covered in
radio-active dust, and so would be, in essence, untouchable
(unapproachable would, probably, be a better term). I am not
familiar with what the Greek alphabet radiations would do to the
information on the magnetic platters, but as this is <b>ionizing</b>
radiation, I am assuming that bit errors due to direct interaction
between highly penetrative, sometimes charged, particles and your
disk's platters is likely.<br>
<br>
If all that failed to destroy your data, then, yes, you are unlikely
to build a Faraday cage strong enough to have your disk survive the
EMP.<br>
<br>
If surviving an atomic holocaust is your goal, go with
geo-redundency. I have set up a system for geo-redundent backup of
the scales you talk about, about four years ago. Back then, it took
us about two weeks of hard work. Today it should be easier, but it
will not be easy. Then again, since you aim to survive a bomb last
used in combat almost 70 years ago, I'm sure you have the money to
pay for your paranoia.<br>
<br>
Shachar<br>
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