Re: DOD erase

On 05-Mar-2014 10:54 -0800, John McKee wrote:

<<SNIP>> My conclusion is that three patterns need to be written to
each sector AND the direction the heads move needs to be reversed and
the three patterns written again to ensure that data will be
unrecoverable. I am wondering if the disk sanitizer programs do
that.

I haven't any idea about the technologies behind actual sanitizing...

But to be clear, the user information I alluded to as remaining on disks, by having used an attempt to /delete/ the data versus having used a drive-level disk-wipe utility, is information that was never lost in addressability to the system nor will that data have ever been overwritten; not even once, not without at least a scratch-install per the disk initializations that feature effects. And AFaIK not even the disk initialization is appropriate, because IIUC, even that action does not actually /clear/ the disks, instead doing just enough work to make /sectors/ usable to the LIC SM, which does not require zeroing\clearing everything. Although filling the disks with rewrite activity along with the essentially random nature of disk write activity is going to be fairly exhaustive, minimally any area that had been /carved out/ for use by the LIC remains effectively untouched by such an algorithm. To assume there will be no user information there, would be a mistake.