Since 2006, hard drives have used a technology called PMR (Perpendicular Magnetic Recording) for data recording.

Before 2006, magnetic particles were "deposited" horizontally on the surface of the platters. Like laying a domino on a table. This means that the orientation of these particles was flat on the surface of the platters. This took up more space and, consequently, it was not possible to create large capacity hard drives.

Then came PMR technology, which consists of "depositing" the magnetic particles vertically. That is, putting your dominoes "upright". They take up significantly less space and, consequently, the density of the disks has increased considerably since 2006 to reach current volumes of more than 4TB of data.

And tomorrow? HAMR technology is gradually emerging from the research laboratories of hard drive manufacturers. By 2020, we should have hard drives with more than 20TB of data.