How much data is left behind after shredding?

When it comes to disposing of old hard drives, you have numerous options at your disposal (no pun intended). 

The key point here is that because data is stored magnetically, it must be removed magnetically as well – and we’re not talking about any run-of-the-mill fridge magnet. Due to the high density of zeroes and ones on a drive, a powerful electromagnet is needed to ensure all data is erased. Destroying a drive by other means – shredding, crushing, smashing with a hammer – does not erase any data; it only breaks it into smaller pieces, like a jigsaw puzzle. And just like a jigsaw puzzle, with the right expertise, those pieces could be put back together!

“But surely,” I hear you ask, “that data can’t possibly be read?” Well, that depends on the technology at your disposal. Forensic recovery companies possess the means to extract data from damaged hard drives. Using an electron microscope, it’s possible to see the existence of data on tiny hard drive fragments. It’s not beyond the realm of possibility to suggest that with the right equipment, one could reassemble and pull data from a destroyed drive.

“But what if I separate the hard drive pieces, or mix them with others?” You might think this would prevent recovery, but there are two important points to consider here. The first is pattern recognition. As you’re putting together a jigsaw puzzle, you soon reach a point where your brain fills in the gaps; you know which piece will go between two similar pieces. Data structure works the same way – if patterns in data can be reconstructed, the data itself can be restored and read. The second point is about data density. To stick with the jigsaw puzzle analogy, imagine each piece of a puzzle has an entire picture printed on it. Even if you had just one piece of the puzzle, you could still view the picture on it without issue. As drive capacity continues to rise, each tiny fragment of smashed hard drive contains more of the complete picture.