How to truly erase all data from your hard disk?
Interesting post from ZDNet buoys an important concept to know, but only barely scratches the surface of the issue.
This ZDNet post brings up a good point: How to REALLY erase a hard drive. You know when you want to delete a file on a machine, it doesn't truly get deleted. It is saved somewhere on the hard disk because hard disks have in-built protection features.
Now it this really something to rejoice? Not really. If you've ever deleted a file while you were being stupid, trust me, it'd be easier to float in the Niagara than to recover your document. I was in a similar soup recently, and searched far and wide (ok, I did start with Google), I even paid for a few commercial ones, but the truth is that erasing a hard drive using pretty much any tool which overwrites the entire drive at least once will make any data on it unrecoverable.
Can someone do it in principle? You know, like those men in white in FBI crime labs? I read recently in Forsyth's The Afghan (and I am sure such examples abound in crime thriller novels and Hollywood) that recovering hard disks was brushed off as a trivial matter. Not quite, not so soon. I asked a friend who's been in reconnaissance in his draft, and he says it's amazing what they *can* recover. For instance, some labs will claim to be able to pull data of a drive put through an industrial chipper – one little bit at a time, on a magnetic microscope, for tens of thousands of dollars.
However, you overwrite it once, and you'll be told the same thing: it is irrecoverable, not even with the microscope.
But since this is actually a post about file recovery and undelete software, I'll include a couple of recommendations: Darik's Boot and Nuke (DBAN) is a superb FREE utility that works well. If you want a paid piece of software, I've tried a few but found R-Undelete to be the best.
If you use Linux, check out this detailed visual guide from Engadget (although there's always the dreaded shred command which is a pretty secure delete as it blasts random data over the file multiple times.)