Layout of HDD
Understand the detailed layout of a hard disk drive, including its main components such as platters, spindle, and actuator arms. Learn about tracks, sectors, cylinders, and metrics like seek and rotational latency. Discover the processes of reading and writing data on HDDs and review their limitations compared to other storage devices.
Introduction
A hard disk drive (HDD) is a nonvolatile storage device used in computers that persists data in a durable way. IBM introduced HDDs in 1956, and they have since become the dominant secondary storage device for general-purpose computers.
Components
Let’s take a look at the different components of an HDD and their roles.
Platter
An HDD consists of one or more circular magnetic plates, called platters, stacked over each other to hold the data. Each platter consists of a nonmagnetic material such as aluminum, glass, or ceramic, coated with a shallow magnetic material 10–20 mm in depth and an outer layer of carbon for protection. Each platter has two working surfaces, one on either side, which holds the actual data.
Spindle
The stack of platters is held together by a spindle motor, which is responsible for controlling and rotating the platters. Most HDD failures are related to the spindle's inability to spin the platters.
Actuator
Each platter has an actuator arm positioned on top of it, which is responsible for reading, writing, and deleting the data on its respective ...