On 27/06/13 11:01, Omer Zak wrote: > 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? This info is from memory, so verify or trust at your own risk.
The US military once activated an A-bomb at a considerable height over the pacific ocean. This caused street lights in Hawai, *900 miles away*, to blow out. In fact, that how we know of EMP in the first place. 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. 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 *ionizing* radiation, I am assuming that bit errors due to direct interaction between highly penetrative, sometimes charged, particles and your disk's platters is likely. 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. 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. Shachar
_______________________________________________ Linux-il mailing list Linux-il@cs.huji.ac.il http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
