With today’s way of life being heavily tied to having access to digital information, it is important to know where all that data goes when you use a computer. While many people know about hard disk drives as data storage, many don’t understand how they actually work. Today, we take a closer look at the inner workings of hard disk drives.
While hard disk drives are available in different sizes, they all feature three key components:
- The platters – Disc-shaped alloys coated with magnetic particles which are divided into countless tiny sectors
- The arm – A thin part that contains the read-write head, responsible for writing and retrieving information.
- The motor – A small electric motor that spins the platter at very high speeds.
How Data Is Stored and Retrieved
When a computer is writing data into the hard drive, the information is written as “bits,” which are technically a sequence of 1s and 0s translated into a physical form by the arm’s write head. It does so by changing the orientation of the particles on the platter’s magnetic surface. Eight bits form a single byte’s worth of data. The bits are arranged in concentric circles called tracks, which are further divided into smaller sectors.
In the past, creating more data storage required manufacturing bigger platters since there could only be a limited amount of sectors in a platter. However, increasing the platter size would have made the hard disk drives too bulky to fit inside a typical laptop or computer case. The development of multi-platter disk drives made it possible for users to have higher-capacity disk drives without them being too bulky. Today’s typical hard disk drives usually have around two to four platters.
When retrieving data, the arm’s read head simply checks the orientation of the magnetic particles and translates the information based on what it scanned. The faster the platters spin, the more bits pass under the arm’s read-write head that get processed.
Because data may be too much to be contained in a single sector, it’s possible for a file to have its data distributed among multiple sectors and even throughout multiple platters. When you access that file, a series of precise actuators maneuver the arm to seek out which parts of the platter have the necessary data. Most hard disk drives available today can process 150 Megabytes (1 million bytes) per second, although there are high-end versions that can process data twice as fast.
Manufacturing the Hard Disk Drives
Hard disk drive manufacturers rely on automated machinery to manufacture hard drives starting from cutting out the alloy metal that will eventually become the platters. Because hard disk platters have to be smooth enough before the magnetic coating can be applied, the alloy has to be ground and coated to achieve a flat surface.
Fabricating and assembling the hard disk drive components require a high degree of precision. For example, the platters are assembled by mechanical arms and linear stages that are programmed to move and stop with only a few microns’ margin of error. This ensures that the cut-out aluminum disc platters have perfectly flat surfaces ideal for the magnetic coating used to store the data.
Aside from employing high precision, automating the assembly process also helps prevent the risk of defects caused by contamination. Even the smallest bit of dust can cause major damage to a hard disk drive. Manual assembly would likely introduce impurities every time workers stepped inside an assembly room, so it is not an ideal method. Furthermore, automated assembly is a lot faster than manual assembly – a very important factor especially since there is always a huge demand for new hard disk drives.
Thanks to constant developments in computer hardware technologies, hard disk drives tend to get smaller while their capacities grow bigger. Tomorrow’s hard disk drives will be able to store data many times more than today’s highest-capacity drives, all while being ultra-compact and several times faster to keep up with the ever-growing demand for more information.