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Data A&E - How Hard Drives Work


A hard drive is made up of 2 or more magnetic disks, each measuring at around 3.5 inches in diameter or 2.5 inches for laptops. It has a motor, spindle, heads, controllers and an actuator. All the components are enclosed in a metal case.

The main purpose of a hard drive is to store data that can be used later. Running a software program, sending and receiving e-mail, saving Word documents and Excel spreadsheets all require data from the hard drive.

The magnetic discs or platters hold the data once it is stored. The controller, heads and actuator arm all play a role in the storage and retrieval of the data. The heads and actuator receive instructions from the controller before any reading or writing to the magnetic platters is done.

A computer sends a message to the controller once data is needed. The controller checks its registry to determine the location of the data. Once located, the controller moves the heads to the place they need to be in order to retrieve the data. The controller then uses the actuator arm to read the data from the magnetic platters attached to the heads.

The motor in the hard drive increases speed when data is read or stored. The motor's moves the spindle that spins the magnetic platters to the speed required. When the platters reach operational speed, the actuator begins to read the data.

The data is sent to the controller buffer after reading. The buffer made from solid-state memory; is faster and more reliable memory source. The buffer's performance is based on its size; a buffer is usually 2 to 8 megabytes of space. The buffer sends the data on to the computer motherboard via a cable. The motherboard then processes the information and handles it in the appropriate way.