Date: Wed, 19 Dec 2012 13:25:03 -0800 From: "Ronald F. Guilmette" <rfg@tristatelogic.com> To: Adrian Chadd <adrian@freebsd.org> Cc: freebsd-hackers@freebsd.org Subject: Re: Another WTF moment Message-ID: <57462.1355952303@tristatelogic.com> In-Reply-To: <CAJ-VmokfpSKqzmYiPhdy53kViXtWuUV8TeGpuY6rkJthdirXVQ@mail.gmail.com>
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In message <CAJ-VmokfpSKqzmYiPhdy53kViXtWuUV8TeGpuY6rkJthdirXVQ@mail.gmail.com> Adrian Chadd <adrian@freebsd.org> wrote: >Wow, I didn't even know this existed! My apologies for not replying sooner. It has been a hectic few days. Anyway, yes, there are two kinds of "hidden" areas that may be present on a hard drive, Host Protected Area (HPA) and then separately also the Device Configuration Overlay (DCO). To be honest, I only found out about these myself a couple of months ago as I was researching the proper way of _completely_ eraseing drives prior to disposal. (Hint: Search out a program called "HDDErase". It clobbers _everything_, including even these two hiddfen areas.) >Would you mind filing a doc PR with this information, along with how >you figured out it was a HPA? Ummm... I'm not sure. I only fill out PRs when I see some specific FreeBSD document that I _know_ is either incorrect or incomplete in some way. I am not immediately aware of what specific FreeBSD document either can or should document this particular somewhat obscure aspect of modern hard disk drives. I mean it is just an obscure hardware feature, not unlike the specialized codes that might be transmitted by pressing button #7 on your 10 button "gamer" mouse. I don't think it is incumbant upon FreeBSD to document all such obscure things. As regards to how I verified my suspicion that the size discrepancy might be due to the presence of an HPA on one of the drives, the following page shows exactly how to do that. (Too bad that it assumes that you have booted to some flavor of Linux, but oh well. There are plenty of LiveCD versions of Linux out there which one can boot from, when & if one needs to check for the presence of an HPA.) http://www.forensicswiki.org/wiki/DCO_and_HPA >I'm sure this is going to come up from time to time and it'd be great >if someone would take the doc PR and turn it into a FAQ entry. Someone? Are you volunteering? Regards, rfg
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