From owner-freebsd-stable@FreeBSD.ORG Wed Feb 21 07:58:19 2007 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 2BAD916C4CB for ; Wed, 21 Feb 2007 07:58:19 +0000 (UTC) (envelope-from wb@freebie.xs4all.nl) Received: from smtp-vbr5.xs4all.nl (smtp-vbr5.xs4all.nl [194.109.24.25]) by mx1.freebsd.org (Postfix) with ESMTP id A1D6C13C467 for ; Wed, 21 Feb 2007 07:58:18 +0000 (UTC) (envelope-from wb@freebie.xs4all.nl) Received: from freebie.xs4all.nl (freebie.xs4all.nl [213.84.32.253]) by smtp-vbr5.xs4all.nl (8.13.8/8.13.8) with ESMTP id l1L7wFCI014423; Wed, 21 Feb 2007 08:58:15 +0100 (CET) (envelope-from wb@freebie.xs4all.nl) Received: from freebie.xs4all.nl (localhost [127.0.0.1]) by freebie.xs4all.nl (8.13.8/8.13.3) with ESMTP id l1L7wEMf053723; Wed, 21 Feb 2007 08:58:14 +0100 (CET) (envelope-from wb@freebie.xs4all.nl) Received: (from wb@localhost) by freebie.xs4all.nl (8.13.8/8.13.6/Submit) id l1L7wE2G053722; Wed, 21 Feb 2007 08:58:14 +0100 (CET) (envelope-from wb) Date: Wed, 21 Feb 2007 08:58:14 +0100 From: Wilko Bulte To: Matthew Seaman Message-ID: <20070221075814.GC53528@freebie.xs4all.nl> References: <20070220215248.3C22216D23E@hub.freebsd.org> <45DB8B8D.6080706@umn.edu> <45DBF4D1.6000708@infracaninophile.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <45DBF4D1.6000708@infracaninophile.co.uk> User-Agent: Mutt/1.5.11 X-Virus-Scanned: by XS4ALL Virus Scanner Cc: freebsd-stable@freebsd.org, Alan Amesbury , Ivan Voras Subject: Re: getting garbage faster using FreeBSD? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 Feb 2007 07:58:19 -0000 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@FreeBSD.org