It would be much simpler to just remove the disk drive and then buy a new drive to replace it. It saves time over cloning and then erasing and you'd have the original to fully clone for the purpose of forensic recovery of the empty sectors. You never want to boot from the disk you try to forensically recover and you'd want to make sure it's only ever put into read only interfaces.
Gary Case
Removing the disk certainly works too; but a forensic image (i.e. not compressed) is just as good, and is much easier to store than a bunch of drives.
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