Date: Sat, 15 Apr 2000 09:52:10 -0700 From: Scott Blachowicz <scott@sabami.seaslug.org> To: freebsd-questions@freebsd.org Subject: Re: Erasing an IDE disk Message-ID: <20000415095209.A58006@sabami.seaslug.org> In-Reply-To: <20000415165532.A16019@strontium.scientia.demon.co.uk>; from ben@scientia.demon.co.uk on Sat, Apr 15, 2000 at 04:55:32PM %2B0100 References: <20000414161657.A35142@sabami.seaslug.org> <20000415165532.A16019@strontium.scientia.demon.co.uk>
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On Sat, Apr 15, 2000 at 04:55:32PM +0100, Ben Smithurst wrote: > > dd if=/dev/zero of=/dev/ad0s2c > > That will only erase slice 2, so that's not really good enough. You > won't be able to erase the whole disk unless nothing on ad0 is mounted > (did you check that; what does "mount" show?). I know...all I had was a small root (just overfilled) partition in my ad0s1 slice. So, I was trying to do ad0s2, then on to ad1. > I think what you'll have to do is to put this disk in another FreeBSD system > as ad1 (or ad2, or whatever), and try erasing /dev/ad1 completely (not > ad1s<something> or anything like that). Or, you could use the fixit CD (disc > 2 in WC sets), and use dd from there. Well...I was initially trying this from the "holographic shell" in the installation process, but I was thinking that maybe something was a little weird in the MFSROOT stuff to give me problems. I checked the "mount" command and didn't see any indication of read-only file systems. So, I booted tried into single-user mode with /kernel.GENERIC and tried again from there. No luck. I didn't get past the "Read-only file system" error that dd reported to me. > As for the person who suggested /dev/urandom, I'm not sure that would be > better. It will use loads of CPU time, both ways will stop a casual nosy > person, and neither way will stop someone who *really* wants the data off > the disk. See <http://www.cs.auckland.ac.nz/~pgut001/secure_del.html>; for > more on this sort of stuff. Yeah...when I went looking for Windoze based disk wiping tools, they talk about doing several passes for "DoD" level wiping. I would think that just writing 0's to the whole disk would take care of it...oh well. > When I returned a disk to a shop recently because it was b0rken, I just > wrote 0x0, 0xff, then 0x0 over the whole disk. Given that when I took > it back they used Windows Scandisk to check if it really was faulty, I > think that was overkill. :-) What did you use to do that? And what OS version? I was pretty sure I should be able to dd directly onto the disk device and was surprised when it wouldn't let me do it. I'd be curious to know why. At this point, what I ended up doing was installing a minimal Windoze NT on the repartitioned disks and ran one of those disk wiping tools over it...that ought to be MORE than enough. Thanx, Scott To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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