getting garbage faster using FreeBSD?

Matthew Seaman m.seaman at
Wed Feb 21 07:30:01 UTC 2007

Alan Amesbury wrote:
> Ivan Voras wrote:
>> The obvious question - why don't you burn the tapes and hammer the disks? :)
> Ah, low-tech.  I know it well.  Still, the last time I did any data
> destruction, I found a 4 Tesla magnet does wonders.  Downsides:
> 	1) Oxford's 90cm bore, helium-cooled magnets aren't that
> 	   common, perhaps because a 2000V/500A power source
> 	   is a bit expensive (solution doesn't scale).

It ain't the PSU that's the expensive bit on a supercon magnet -- it's the
liquid Helium.  After all, once you've ramped the current in the coil up to
$bignum amps, it just keeps going so long as the superconductors aren't
allowed to heat up. LHe costs about the same as good whiskey, and you need
gallons of the stuff every few weeks.

> 	2) The hard drive has a tendency to fly out of one's
> 	   hands while moving it through the lines of force
> 	   (solution requires some physical coordination).

Hmmm.... a solenoid coil magnet has a field that is approximately dipolar.
Forces vary as the inverse *cube* of the distance away from the center of
the magnet.  Move a centimeter too close and the drive will suddenly be
ripped out of your hands harder than you can resist.

And sticking lumps of magnetic material up the bore of a 4T magnet
probably requires quenching the magnet in order to get it out without
damaging the magnet...  Can you feel your accounts department wincing

> It's primarily for item #1 that I hadn't mentioned this earlier, as most
> readers of -STABLE users are probably looking for a more scalable solution.

Everyone should have their very own NMR spectrometer in their living room!



Dr Matthew J Seaman MA, D.Phil.                       7 Priory Courtyard
                                                      Flat 3
PGP:         Ramsgate
                                                      Kent, CT11 9PW

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