Date: Fri, 21 Jan 2005 08:50:42 -0600 From: Greg Barniskis <nalists@scls.lib.wi.us> To: Ian Moore <imoore@picknowl.com.au> Cc: Anthony Atkielski <atkielski.anthony@wanadoo.fr> Subject: Re: FreeBSD I LOVE YOU Message-ID: <41F116C2.40008@scls.lib.wi.us> In-Reply-To: <200501220027.11740.imoore@picknowl.com.au> References: <200501200929.j0K9TXbl022106@mp.cs.niu.edu> <20050120151005.GA99300@gravitas.thebunker.net> <1792034180.20050120161719@wanadoo.fr> <200501220027.11740.imoore@picknowl.com.au>
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Ian Moore wrote: > Tape de-gaussers usually aren't much good - they were mostly made for erasing > open reel tape that used ferric oxide particles. > Backup tapes normally use metal particle tapes that need a much stronger > magnetic field to effectively erase them. More powerful degaussers are available, like the one found at http://www.datalinksales.com/degaussers/hd1.htm Not cheap (about $5k if memory serves), but seems to do the job on both HDs and modern tapes (what the company calls "coercive media"). We have not found it necessary to remove the HD platters from their enclosures, although I imagine that might yield more thorough results. We just make two passes for better peace of mind. I also imagine that data on degaussed platters might still be available to the kinds of inspection techniques used on platters overwritten with random data, but our acceptable cost/reward balance tops off somewhere above preventing casual inspection and below stopping the NSA. One way that degaussing is more effective than random data writing is that the disk's servo tracks are also destroyed, meaning you'd probably need to return the device to the OEM for factory reconditioning before anyone could usefully attach it to another computer. I hope it's true, as that was our primary justification for the cost of the degausser. -- Greg Barniskis, Computer Systems Integrator South Central Library System (SCLS) Library Interchange Network (LINK) <gregb at scls.lib.wi.us>, (608) 266-6348
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