Data storage on computers, phones, even smart home devices—all have a hard drive, also called a hard disk, to save information. It’s so commonplace that we probably don’t think about it much, just like we rarely consider what our brains store daily. But however unnoticed, we can’t do without it. And good news: deleting information from a hard drive is much easier than from our memory. Here’s how it works:
How data is stored
How data is stored depends on the medium. A medium could be an old-fashioned floppy disk, but also a CD, DVD, MicroSD card, USB stick, traditional hard drive, or SSD. These data carriers have different properties, but they all have one thing in common: data is stored as zeros and ones. Whether it’s a Word document or a photo—for example, the letter A is stored as 01000001.
The zeros and ones can be compared to a light bulb being on or off. What “on” or “off” means depends on the medium. For example, on a CD or DVD, a laser beam is either reflected or not. On a floppy disk and traditional hard drive, magnetism is used. On MicroSD cards, USB sticks, and SSD drives, it’s electrical charge.
Deleted doesn’t always mean gone for good
Because stored data can contain sensitive information such as passwords, it’s important to protect it. When the medium is still in use, data can be encrypted. Someone with access to the hardware but not the key won’t make sense of the zeros and ones. But if the medium is no longer needed or is passed on, it’s crucial that third parties cannot access old data. In that case, data destruction is necessary.
How data is destroyed depends on the medium. Pressing the delete key usually isn’t enough because the file isn’t truly removed: only the pointer to the file is deleted. In a book analogy, it means a chapter remains but the table of contents no longer references it, so the chapter can’t be found. Because the data (the chapter) is still there, special tools can often recover unencrypted data. The same applies to formatting, which deletes the entire table of contents.
Options for permanent data destruction
So how should it be done? For permanent data destruction, it’s better to use the following methods:
Destroying the hardware
When CDs and DVDs are permanently recorded, data can only be made permanently unreadable by physically damaging the medium. A few deep scratches or breaking the disc will do. Similarly, a hard drive, USB stick, or MicroSD card can be destroyed. Shredding hardware guarantees success in destruction.
Overwriting data
The downside of hardware destruction is that replacement is required, which is costly. An alternative for temporary storage media is overwriting the data. On rewritable CDs or DVDs, the laser reflection pattern is re-recorded. Because of the small data size, the chance this is complete is high. On hard drives, the chance of overwriting all old data by saving new files is small—like placing a chair in a gymnasium with only one chair: it’s unlikely someone will place a new chair in exactly the same spot.
Wiping data
For media with larger storage, the best way to permanently remove data is wiping (in English: wiping). Wiping means rewriting all zeros and ones on the medium, usually with random data. Because by chance some random bits might match original data, this process is ideally repeated several times to ensure success.
When choosing to wipe data, special software can be used. Reuzado ICT Services favors Blancco software, certified by international standards such as ISO. This software makes completely and definitively removing data easy without damaging the hardware.
If you need help destroying your data or are unsure which method suits you best, please contact us at +31 (0)23 551 98 21 or info@reuzado.nlWe are happy to advise and assist!
Author: Dr. Erlijn van Genuchten