How Does a Hard Drive Store Information?

Introduction

Hard disk drives can be found in many of the personal electrical devices on the market today. The basic hard drive holds up to 40 gigabytes of storage space. It is a type of non-volatile storage medium that is able to hold information without a power source being connected. Hard disk drives quickly grew as a main storage medium for computers after being introduced in 1956. It became popular because of its reliability and quick writing speed.

The Hard Drive Components

The hard disk is made up of a mechanical and electrical system. The mechanical system is the individual disks (that hold the data) and the actuator arm (that reads and writes memory). The electrical system (the controller card) is used by the hard disk drive to control the actions of the mechanical system. The controller card also acts as a holding cell for the data going to and from the disks.
The disks in the mechanical system are broken down into individual tracks. Tracks -20 to -1, which are called the service area, are reserved just for the hard drives' operating system. Tracks 0 and up are known as the user area and are used for storing information by the user. The tracks are cylinder-shaped rings and are made up of magnetized participles. The tracks are then broken down into sectors. Each sector has a fixed amount of bytes available to it. The drives usually cluster these sectors together before storing and retrieving data from them.

Process of Storing Data

Two processes have to be done to completely store information on the hard drive. The first is called low-level formatting. This is when the hard drive gets a request to store data and then proceeds to find an available location for it. The hard drive locates available sectors and verifies that there is enough space for the data that is to be stored. If space is available, the track reserves this space for the data; the data needs to be reserved just in case two programs are trying to store data at the exact same time. The information about the location of the reserved space is then sent back to the disks before storing is actually done.
The next step is known as high-level formatting. This process is when the disk uses the sector location information it was given from the previous process to prepare the disk drive to hold the data. It does this by writing the structure of the file storage to the sectors before it writes the data. The actuator arm is then used to write the data onto the disk in the predetermined location. The hard drive then receives a confirmation if the data is written correctly or an error message if there was a problem. The message (error or confirmation) is relayed back to the user.