Today I had a clear out of that cupboard containing all the old motherboards, spare power supplies, cables, converters, and hard disks – all computer geeks have one of these. In my case I had three old desktop hard drives that failed some months ago and were in need of disposal.
Of course, you should never dispose of a hard disk (working or non-working) without first taking steps to ensure the data is unrecoverable. Even though my drives had failed and were not even visible to the host computer when connected, the problem may have been something as simple as a failed drive motor . This could easily be replaced by somebody attempting to recover the data. The chances are high that my data was still intact on the drive platters themselves. As hard drives contain huge amounts of our personal data, the potential for identity theft and fraud is huge. This isn’t paranoia – several studies have been done on this issue, including this one from MIT and this one from Science Daily. So, exactly how do you destroy the data on a hard disk?
Working hard disks
If your hard disk still works (perhaps you are just upgrading to a higher capacity model), a good option is to wipe the data. Note that I said ‘wipe’ – not ‘delete the data’, ’empty the recycle bin or trash can’, or even ‘format the disk’. None of those actions are enough to permanently remove data from your hard disk. A quick Google search reveals many tools for recovering such data.
To truly erase data, it needs to be overwritten by other data (‘disk wiping’). There are a number of tools to do this; they simply overwrite every single bit of data on your disk with a random 0 or 1. Most of the tools also make several passes because with very advanced tools it can still be possible to recover the data after a single wipe. The US Department of Defense standard requires 7 passes for secure data deletion. You probably don’t need to go that far (and with large hard drives it takes a long time). A popular tool to achieve this is Darik’s Boot And Nuke (www.dban.org). With the data securely wiped you can be sure it cannot be recovered. However, if your disk has failed in some way, or simply if you are not donating it to another user, why not have some fun with some physical destruction too?
Non-working hard drive: Hello physical destruction
If your hard drive has failed you will be unable to use disk wiping tools, so you need to resort to physical destruction. It is not unusual for data to be recovered from hard drives that have been in fires, been submerged under water, or run over by vehicles. Data recovery specialist even recovered 99% of the data from hard drives that were aboard the space shuttle Columbia. The key to ensure data is lost is to damage the disk platters which are inside the strong metal protective case. Only when they are damaged can you be sure of preventing recovery.
Method 1: Drilling holes
One common method of physically destroying drives is to drill holes in them, all the way through the disk platters. However, this is easier said than done. Here is one of my hard disks after an attack with a drill:
As you can see, the drill hole (bottom, right of centre) has gone through the outer casing (which is actually quite thick) and has pierced right down to the disk platter – but to do this you need a strong drill bit and a lot of pressure. To be extra sure it would be a good idea to put several holes in the platters (and remember that disks contain multiple platters), but this seemed like a lot of work. There must be something more fun…
Method 2: The hammer
Sometimes you just need to go back to basics: pure physical force. Unfortunately, although hard disks might be relatively delicate while in use, their strong metal cases mean they can actually still withstand quite a beating, as you can see below.
Here is my hard disk after sustained attempts to destroy it using the hammer. It actually lasted quite a long time before failing catastrophically, with the case splitting open. Even after this the disk platters look relatively intact (though admittedly quite bent). It probably still needs a bit more force to properly destroy the platters.
Computer hardware, of course, should never just be thrown in the trash: the environmental impacts of e-waste are huge and long-lasting, so appropriate disposal is essential. Unfortunately where I live there appear to be no manufacturer take-back schemes or safe recycling centres, so it looks like my now shattered hard drives will still be with me for a while longer.