Possible Duplicate:
Erasing data before selling a computer
How do I wipe my hard drive?
On my iMac that I had, it had a process where it met some government standard in terms of safety by going over the drive 7 times.
Possible Duplicate:
Erasing data before selling a computer
How do I wipe my hard drive?
On my iMac that I had, it had a process where it met some government standard in terms of safety by going over the drive 7 times.
Use DBAN.
Darik's Boot and Nuke ("DBAN") is a self-contained boot disk that securely wipes the hard disks of most computers. DBAN will automatically and completely delete the contents of any hard disk that it can detect, which makes it an appropriate utility for bulk or emergency data destruction.
If you want to make the drive unrecoverable, I think your best bet is to remove the platters and take a belt sander (or sand blaster) to them. By ripping off the magnetic coating, you'll insure that nothing can ever be recovered. Obviously, doing so makes the drive useless, but for maximum protection, you can't beat destroying the magnetic media.
Another approach would be to use a heat gun (or blow torch) and a putty knife to scrape the magnetic coating off. This is bad because who knows what the fumes will contain, but you won't have a load of who-knows-what dust around the workshop.
Another approach would be dropping the platters in an appropriate acid, but I'm not enough of a chemist to know which one would work best.
I don't think much of the drill method proposed by another poster - it only destroys part of the surface, making recovery of only some of the data impossible.
If your objective here is to remove any possibility of recovery EVER, then you really need to attack ALL of the magnetic media on the entire surface. Anything you can do that turns the magnetic media into particulate matter is going to be sufficient.
Of course, as far as we know, no one's ever recovered data from a drive after it's been over-written with zeros. So, it really just depends on how paranoid you are.
You can also check out File Shredder, a free Windows utility to delete files securely.
You could use a Linux Live-CD and dd
together with /dev/null
and/or /dev/random
:
dd if=/dev/random of=/dev/sda bs=1M
cp
too, see Wiki article about dd (Unix). The effect is perfect, you don't need to do it twice.
If you want it completely non-retrievable, get a drill and bore holes in the thing. As well as leaving holes, it warps the drive platters and makes retrieval impossible.
See Sanitizing hard drives at the hardware level. The tool it links to is DOS-based and may or may not work on an Intel Mac, but you might be able to find a similar tool which is designed for Mac. If not, you can always plug the drive into a PC.
Its advantage over programs like DBAN is that it uses an ATA command built into all modern hard drives which gets the job done quicker and more securely than any software can.
After wiping the drive, recycle it if you can rather than discarding. In Australia there's Byteback for (free) recycling of computer parts.
Just perform a full format (no quick formats here!) on it. Unless you're a government official who stores nuclear launch codes, it'll be enough to stop recovery.
The way file recovery programs work is scanning the disk for data that looks like a file - it can't find it because it's place in the file table is missing. A quick format just wipes the file table, whereas a full format fills the hard drive with zeros. A "secure" format fills the hard drive with zeros. Several times. More secure? Yes. Necessary? Not for most of us.
Of course, it feels really, really good to do it, so I recommend Boot and nuke.