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.)

PS: If you're really, really destroy­ing a hard disk for legal or other rea­sons, you shouldn't be read­ing google stuff any­way. Toss the disk into an sear­ing oven and you can rest assured there's very lit­tle recov­er­able from melted metal ;)
  • Sarah

    With the DBAN if I want to use it can I just erase what I want off of the hard drive or does it erase every­thing automatically?