MicroNugget: What are the Different Components in the Mechanical HDD?

In this video, Anthony Sequeira covers hard disk drives, how they do what they do, and all the components that make it possible. Mechanical hard disks are rarer today than in days past, but storage engineers should still know their parts and how they work.

First is the platter. This rigid surface is incredibly, unbelievably smooth. Made of glass or aluminum substrate and covered with a magnetized surface, any warping or imperfections on the platter can lead to crashes or "noise".

The spindle is the axle that rotates the platter at staggering RPM. The most common speeds it provides are 5,400, 7,200, 10,000, and even 15,000 RPM — the drive motor keeps the spindle flying along.

The actuator arm assembly carries the read/write heads back and forth into extremely precise positions over the platter. Those read/write heads hover over the platter at an incredibly close so-called "flying height" — roughly the diameter of a human hair.

These components combine with storage concepts of internal addressing and other computational principles to mechanically store incredible sums of information.

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