How do you destroy an old hard drive?

Physical destruction of a drive is tricky business. There are many companies that deal specifically in the field of data destruction, so if you are doing any kind of mass you may want to at least look at their price list. If you contract, make sure the company is properly bonded/insured, and provides audit trails for each destroyed item. In the worst case scenario that your information does get out, you want the document in hand that says your contractor properly destroyed the item in question. Then, at least, you can transfer the liability.

When it comes to drive destruction you typically see one of two main fields:

1. Disk Degaussing
2. Physical Destruction

Degaussing

Degaussing used to be the norm, but I am not such a big fan. On the plus side it is fast, you'll normally just dump the disks on a conveyor belt and watch them get fed through the device. The problem is auditability. Since the circuitry is rendered wobbly, you won't be able to do a spot check of the drives and verify that the data is gone. It is possible, with some level of probability unknown to me, that data could still exist on the platters. Retrieving the data would, without question, be difficult, but the fact still remains that you cannot demonstrate the data is actually gone. As such, most companies now will actually be doing physical destruction.

Physical Destruction

At the low end, say a small box of drives at a time, you'll have hard drive crushers. They're often pneumatic presses that deform the platters beyond useful recognition. At the risk of supporting a specific product, I have personally used this product from eDR. It works well, and is very cathartic.

At a larger scale, say dozens or hundreds of disks, you'll find large industrial shredders. They operate just like a paper shredder, but are designed to process much stiffer equipment. The mangled bits of metal that are left over are barely identifiable as hard drives.

At an even larger scale you can start looking at incinerators that will melt the drives down to unidentifiable lumps of slag. Since most electronics can produce some rather scary fumes and airborne particulates, I would not recommend doing this on you own. No, this is not a good use of your chiminea.

Manual Dis-assembly

If you are dealing with one or two drives at a time, then simple dis-assembly might be sufficient. Most drives these days are largely held together with torx screws, and will come apart with varying levels of difficulty. Simply remove the top cover, remove the platters from the central spindle. Taking a pocket knife, nail file, screwdriver, whatever, have fun scoring both surfaces of each platter. Then dispose of the materials appropriately. I cannot speak to how recoverable the data is afterwards, but it is probably sufficient. The biggest thing to keep in mind is that while most desktop hard drive platters are metal, some are glass. The glass ones shatter quite extravagantly.

You should also take care of removing and destroying the memory chips on the board because of cache memory and (with "hybrid" drives) of NAND chips containing up to 4GB of cached data.
A good way to do that is to wrap the board in linen or another coarse cloth and hammer it, that should keep broken parts from flying everywhere.

Additional Considerations

Before you decide on a destruction method, make sure to identify what kind of data is stored on each device and treat it appropriately. There may be regulatory or legal requirements for information disposal depending on what data is stored on the disk. As an example, see section 8-306 of DoD 5220.22-M.

For hard drive destruction, DoD 5220.22-M section 8-306 recommends: "Disintegrate, incinerate, pulverize, shred, or melt"

All that being said, performing a single pass zero wipe is probably sufficient for your purposes. Modern research indicates that modern hard drives are largely immune to the "magnetic memory" problem we used to see on magnetic tape. I would never bother doing anything more on a household drive unless the drive itself was exhibiting failures.

Your hard drive will undoubtedly contain toxic substances which if heated or burned will be released into the air, not a good thing. If you did this in your oven you would never want to use your oven for food again!

Much better to take the entire drive as is and simply chop it into many pieces. A sheet metal shear should be able to slice through it like butter. Any good machine shop should have one. Alternatively if you know a fireman have them use the jaws of life on it; those things will cut through almost anything.

Once your drive is transformed into 10-20 little pieces you should have little worry that anyone will get data off it again.

1. dismantle components using a screwdriver and dismantle the plates
2. put components in a bag
3. pour petrol over and in the bag containing components
4. make sure a fire-extinguisher is close by (Safety first!)
5. put the bag in fireproof pot and light it on fire with a long match
6. Do not breath the fumes, they can be toxic

Note : You can use thermite instead of petrol.

Now maybe this is not the most environment friendly way to do it, but it does work!

Should you have a real incinerator, I would use that, since it is a lot more efficient and safer.

Another option which is safer but not as spectacular is to dismantle the hard drive and grind the platers.