How do I destroy a hard disk?

Question

I have an old hard disk (Maxtor 250Gb) from about 3 years ago that started giving errors and now sits in a draw in my desk. It has some confidential data on it but it's unlikely that it can be read because the disk started to go bad. However, before I dispose of it I want to make sure that the data can't be recovered by destroying the disk.

What is the best way to destroy the disk such that the data can't be read? (I live in Arizona and was thinking of leaving it in the yard when we have those 125 F days...?)

What is the best way to dispose of the disk after it's destroyed? (I believe that it's environmentally unsound to chuck it in the trash.)

Answer 1

If you are looking for standard procedures and reliable methods, you could read the Guidelines for Media Sanitization (PDF) of the National Institute of Standards and Technology.

For any given medium there a three basic methods:

• Clear
• Purge
• Physical Destruction

For hard drives they recommend:

Clear:

Overwrite media by using agency-approved and validated overwriting technologies/methods/tools.

Physical Destruction:

• Disintegrate
• Shred
• Pulverize
• Incinerate: incinerate hard disk drives by burning the hard disk drives in a licensed incinerator.

Purge:

1. Purge using Secure Erase. The Secure Erase software can be download from the University of California, San Diego (UCSD) CMRR site. Purge hard disk drives by either purging the hard disk drive in an
2. NSA/CSS-approved automatic degausser or by disassembling the hard disk drive and purging the enclosed platters with an NSA/CSS-approved degaussing wand.
3. Purge media by using agency-approved and validated purge technologies/tools.

Degaussing any current generation hard disk will render the drive permanently unusable.

Answer 2

Thermite is the Ultimate Solution. (To both data erasure and many other problems)

Answer 3

It shouldn't be that hard to expose the platter after peeling back the various stickers covered in dire warnings. Once exposed, you have a choice of fun methods. Bending it even a little would make spinning it under a head impractical, so that is probably a good place to start. A ball peen hammer could be used to make a nice texture, or just apply a belt sander. Wear eye protection, naturally.

Pragmatically, unless you are holding national secrets, just scoring the platter with a scratch awl really ought to be sufficient to make it well beyond anything but the NSA's capability. If you are really worried, score both radially and in spiral.

Hand the wreckage (or at least the bits you don't hang up as a trophy) over to an E-Waste recycler and they will do something appropriate with it.

Answer 4

A combination of really strong magnets and a sledgehammer is really the only way. In that order.

Answer 5

One quick and easy way, recommended by Steve Gibson, is drill a hole through the hard drive making sure you drill through all the platters.

Answer 6

I've used DBAN extensively.

Darik's Boot And Nuke creates a bootable CD/floppy. You boot to it, and, after it picks up your hard drives, you can select as many drives as you want and then the method of destruction (we usually 9 or more passes of random 1s and 0s).

Simply overwriting 0 0 0 0 over and over can still leave data recognizable.

Answer 7

See if your company already employs a bonded security firm for shredding documents. I use ours for shredding reports, digital media, old backup tapes, and hard disks. IIRC, it costs two bucks per hard disk, and they grind 'em to powder. No fuss, no bother, no eco-issues.

Answer 8

Basically if it still works, use some utility, that overwrites each sector of the disk at least 10 times. Easily done for example with dd.

As for disposing of it, it's basically iron and it's alloys. Just throw it into metal recycling container.

Answer 9

My company owns a hard drive degausser for just this purpose, nicknamed the "shredder". They get nuked before disposal of old server or PC hardware.

Answer 10

Related:

• Secure Formatting Disks
• Sugestions for cleansing PC’s before recycling / disposal

Besides of that I would go with a big hammer...

Answer 11

The quick and dirty way is to unscrew the casing, remove the magnets (as these can be fun) score the platter you can see and fill with sand and shake.

Not 100% unrecoverable but practically close enough unless there are state secrets on it.

Answer 12

Sledgehammer+backyard fire=win

Answer 13

With GNU shred and a very heavy hammer.

Answer 14

Drill 3 holes in the hard drive. Proved to make the drive irrecoverable.

Answer 15

Use DBAN. It's extremely powerful, conforms to several standards for data removal (including Department of Defense requirements), and runs from a boot media. It's also freely available.

Furthermore, if you require certification regarding these standards, they offer an enterprise (non free) version which includes this.

I implemented this as SOP at both IBM and Emerging Health Information Technology, not to mention in the financial sector.

Answer 16

The NATO guidelines on the destruction of magnetic data-holders is that the medium should be dismantled as far as possible and the magnetic layer should be either shredded with snippets of less then 0.25 by 0.25 millimeter, pulverized, melted or dissolved.

In practice we took the lint out of backup tapes and put that into a shredder (work the same with floppy disks) and the snippets was treated to an acid bath by a specialised company.

Hard disk was another matter, we took the platters out and sanded it down till we had bare metal. We used a belt sander for that, that does the job very quickly. The platters (and the read/write head - talk about paranoid) where then escorted to a specialized recycle company and melted down.

Although degaussers are also certified by our local friendly security agency, they still use the above method internally (well it is a while back so they may have changed there methods).

BTW, the dust of the harddisks make a rather decent thermite :-)

Answer 17

First you perform one of the options listed in splattne's answer and then you turn the drive into an approved electronic waste facility. Don't throw it in the trash, bury it in the yard, deep six it, or anything else. I have a bucket of them in the garage that have been sanitized and are awaiting drop off at the next free e-waste recycling event, along with some CRT monitors. If they only accept "whole" computer cases, then open one up and fill it with the sanitized drives, they never look inside.

Of course I have heard that some of this stuff winds up in shipping containers destined for a poor African country where kids throw it into piles of burning tires and collect the slag metal after all the plastic has burned away, and then they sell it for ten cents a pound. Hopefully this other end of the "recycling" process will improve someday.

Answer 18

For the drives that spin up and can be addressed, use the following command to "zero" out the drive:

dd if=/dev/zero of=/dev/harddrive bs=1M

If you're really paranoid, do it 8 times, but to my knowledge, no one has ever recovered from one without pulling the platters and examining them microscopically. There's actually been an ongoing challenge since 2008: http://16systems.com/zero.php

If the drives DON'T spin up, 5 or 6 good wacks with a hammer will take care of the platters.

Answer 19

the ultimate boot cd (UBCD) has many wiping tools that are good and easy/fast to use :)

otherwise you can open the drive and clean the platters with windex haha

Answer 20

When decommissioning clusters of machines in the past we have used a gas powered nailgun through the drives, making sure to catch the platters.

Perhaps not the most environmentally friendly option. But it is satisfying and you can get through quite a few at a time.

Answer 21

Throw it in a volcano. You have those in your neighbourhood, right ?

Or an oven ... just like grandma's cookies ... let it burn at maximum for half an hour (should melt everything but metal).

Answer 22

I once worked at a Medical Device Manufacturer who sold PCMCIA Hard-drives for storage of ECG data. Occassionally a defective drive would come back with patient data. We found that if you slapped the drive down hard enough on a work bench, the glass platters would shatter with a satisfying crash, and if you opened the case, the platter came out as a powder. Our compliance department decided that this would meet HIPAA requirements.