getting garbage faster using FreeBSD?

Wilko Bulte wb at
Wed Feb 21 07:58:19 UTC 2007

On Wed, Feb 21, 2007 at 07:29:21AM +0000, Matthew Seaman wrote..
> 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.

Sounds like what the military are experimenting with: magnetic rail gun.

> > 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.

I once had business with a customer from the military who wanted to 
permanently decommision some disks.  I proposed a main battle tank.
And, apparantly they saw the fun in that, they reported back that 
gently rolling one over a disk indeed does the trick nicely.

So when you do not want your living room spoiled by a 4T magnet go and
find a surplus Challenger tank (when in the UK) or a M1A1 Abrams (when in
the US).

Plasma torches like found in car body repair shops also do it just fine.

Wilko Bulte				wilko at

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