Technically it's possible for "residual magnetism" of the original data to make it become visible again. When a data pattern is stored a long time, neighboring particles "pile on" to reinforce the signal, whether a one or a zero, so the "old signal" is actually stronger than a new one. After many recordings, each scrambled in a different way, that residual pattern fades. These effects differ with minor changes in media, head, and recording signal technology. While this stuff is true and verifiable in a lab, only the paranoid and NSA types might care or be able to find these residual signals. So.. there's a reason for repeats, and the software utility people can't anticipate what a specific drive really needs so it's usually "sufficient overkill". Chuck > -----Original Message----- > From: tclug-list-bounces at mn-linux.org > [mailto:tclug-list-bounces at mn-linux.org]On Behalf Of Justin Kremer > Sent: Friday, January 23, 2004 2:31 PM > To: TCLUG Mailing List > Subject: Re: [TCLUG] Hard Drive eraser - linux on a floppy > > > On Fri, 23 Jan 2004, Chris Frederick wrote: > > > Um... couldn't you just get any bootable linux distro, and do a > > dd if=/dev/urandom of=/dev/hd?? > > or > > dd if=/dev/zero of=/dev/hd?? > > and achieve the same effect? Why would you need 50 passes? Isn't one > > enough? > > > > Chris Frederick > > Well, maybe you don't need 50, but more than one at least. > Here's the first link I found from this mailing list. I know this has > been discussed multiple times, but I can't seem to find the right words to > search for in google. > http://archives.real-time.com/pipermail/tclug-list/2002-November/054257.html > > ------------- > Justin Kremer <kremer at ringworld.org> _______________________________________________ TCLUG Mailing List - Minneapolis/St. Paul, Minnesota http://www.mn-linux.org tclug-list at mn-linux.org https://mailman.real-time.com/mailman/listinfo/tclug-list