How does a Hard Drive Work?
Most of the time, people don’t want to know how a hard drive works, simply that it does. But modern hard drives are actually a miracle of modern engineering, allowing for billions and trillions of little bytes of information to be stored in a small, portable package and accessed at incredible speed. Considering the speed and forces involved it’s amazing that hard drives are able to work so well, diligently reading and storing data in all kinds of conditions.
All hard drives have four basic parts: the platter, the spindle, the head, and the actuator. The platter is a thin sheet of metal coated in tiny magnetic particles that can be aligned in one of two ways. It is this alignment which corresponds to the 1s and 0s of binary code, the basis of all computer programming. The magnetic particles are so small that they are impossible to see without a microscope, and must be carefully applied as a nanometer-thick coating to the platter itself. The platters are held together on a spindle, which not only stores them, it spins them so that the “head” can read them and scan them for information. There are generally a great number of platters inside a single drive, and modern hard drive design allows for writing on both sides, as well as the manufacture of almost impossibly thin platters so as to maximize available space.
It is the head that does all of the real work of the hard drive, since it is capable of reading and writing all of those little magnetic 1s and 0s on the platter. It is moved around by the actuator. Most hard drives have a large number of heads, one for each platter. These heads move at incredible speeds and are capable of reading the platters with such speed that they appear to human eyes to be everywhere at once. The head is kept from coming into contact with the hard drive (and thus damaging it) by a thin cushion of compressed air caused by the speed at which the platters rotate. However, if the hard drive is subject to sudden shocks, it is possible for the head to come into contact with the hard drive, resulting in a “crash” which irreparably damages the hard drive. Modern designs generally have shock absorbers built into the actuator in order to prevent this, especially on models intended for use in laptops.
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