How Does a Hard Drive Work?

By Tiesha Whatley


The hard drive is what a computer uses to store all of its data and programs. Even when the computer is turned off, the hard drive is still able to retain the data. As computer systems become more complex, the roles that the hard drive plays have increased. In this article, we will learn the hard drive's biggest role in keeping a computer running. We will also understand how the hard drive stores and retrieves data.

About the Hard Drive

A hard drive is made up of 2 to 5 magnetic disks, each measuring at around 2.5 inches in diameter. It also has a motor, spindles, heads, controllers and an actuator. All the components are encased in metal.The main purpose of a hard drive is to store data that can be used at a later time. Running a software program, sending and receiving e-mail and saving Word documents and Excel spreadsheets all require the data from the hard drive. The magnetic platters hold the data once it is stored. The controller, heads and actuator arm all play a role in the storing and retrieval of data. The heads and actuator receive instructions from the controller before any reading or writing to the magnetic platters is done.

How it Works

This is a brief description of what happens when a request for data is made by the computer. The computer sends the message to the controller once data is needed. The controller checks its registry for the location of the data. Once the data is located, the controller moves the appropriate heads to the place they need to be. The controller then uses the actuator arm to read the data off the magnetic platters that are attached to the heads.The motor in the hard drive speeds up when data is read or stored. The motor's job is to operate the spindle that spins the magnetic platters to the speed required. When the platters reach their full operational speed, the actuator starts to read the data. The makeup of the hard drive is similar to that of an old record player; the record is the magnetic disk and the needle is the actuator.The data is sent to the controller card's buffer after it is read. The buffer has solid-state memory; a more faster and reliable memory source. The buffer's performance is based on its size; a buffer is usually 2 to 8 megabytes of space. The buffer then sends the data on to the motherboard through a cable. The motherboard then processes it and handles it in the appropriate way.