Hard Drive INSIDE — The Complete Internal Structure Explained at Microscopic Level | How HDD Works

Key Takeaways

Inside your computer, a disc spins 120 times every second. A tiny needle flies above it. Gap thinner than your hair. Look inside a hard drive. There are only few main parts. A shiny disc, a metal arm, a motor, and a circuit board. This shiny disc is called a platter. It looks like a mirror. Your photos, videos, everything is stored on this disc. On top of this smooth metal, there is a very thin magnetic coating, invisible to your eyes. This is where data actually lives. Below the platter, there is a small but very powerful motor. It spins the platter at incredible speed, non-stop, day and night. At the very tip of this arm, there is a tiny piece called the readr head. This is the most important part. Every bit of data, every photo, every video lives or dies based on this tiny head. This head never touches the disc. [music] It flies just 10 nanometers above the surface. How small is that? [music] 1,000 times thinner than hair. Now, let us zoom in very, very deep into the magnetic surface of this disc. What is hiding [music] on this surface? Billions and millions of tiny magnetic grains so small no human eye can ever see them. Each grain behaves like a tiny magnet. Each tiny magnet has a north and south pole. When the north pole points one direction, it means one. Opposite direction means zero. Now how does the head write data? Inside the head there is a tiny electromagnet. When electricity flows through it, it creates a magnetic field. To write one, current flows one direction. The magnetic field flips the tiny magnets north to the right. One is written. To write zero, current flows opposite direction. The magnetic field reverses. North flips to the left. Zero is written. Simple as that. Eight bits together make one bite. Just eight tiny magnets in a row on the disc. One bite is enough to store one letter. ADA is not written randomly on the disc. The platter has thousands of tiny circles called tracks, like rings on a tree, one inside another. Each track is divided into small sections called sectors. One sector can hold 512 bytes of data. When you save a photo, the computer breaks it into many small pieces. Each piece goes into a different sector on the spinning disc. But how does the hard drive remember where each piece is stored? It keeps a special list like a map of your data. Now let us read data back. The arm checks the map, moves to the correct [music] track. The head flies over the spinning magnets below. As each magnet passes under the head, it creates a tiny electrical signal. North right means one. North left means zero. These tiny electrical signals travel through a thin ribbon cable to the green circuit board at the back of the hard drive. The controller organizes the ones and zeros, then sends them through a SATA cable to the motherboard, then straight to the processor. The processor reads these ones and zeros, understands them, and converts them into your photo, your video, your game,