What Are the Functions of Hard Drives?

One of the most necessary parts of a computer is the hard drive. Besides storing digital information, hard disk drives also contain all of a computer's operating data, including the operating system. In configurations with multiple hard drives, they are also useful in backing up data for archival purposes.

Storage

Hard drives are designed to store large amounts of digital information. This is accomplished by writing the binary data to a series of rotating magnetic platters. When the platters containing data are spun, the magnetic profile is read and the data can be detected and reconstructed by the computer. Hard drives are attached to the computer's motherboard, which governs the writing and reading of information.
All of the data displayed on a computer, including pictures, music, video and text, are stored on the hard drive. Additionally, the applications that display this content and allow users to modify it are themselves stored on the hard drive. For this reason, larger hard drives are always desirable, and new generations of PCs are expected to contain larger storage capacities.

Operating System

A computer's hard drive also contains its operating system. In cases where multiple hard drives are accessed by the same computer, or when a single hard drive is partitioned into multiple sectors, the portion that contains the operating system is known as the startup disk. This is the hard drive that the computer will access when it is turned on, booting the operating system and eventually displaying the user's familiar desktop interface.
Some users involved in advanced computing prefer to maintain a separate hard drive that contains only the operating system. This can result in a faster startup and better overall performance. Also, it allows users to change or upgrade their operating system without the need to transfer other data stored in the computer on other hard drives.

Archiving

Hard drives are also used for long-term storage of digital information. Servers maintain large amounts of data and allow it to be accessed by all computers on a network. Massive server farms, where each piece of information may be stored multiple times for security purposes, feature banks of hard drives and may represent investments of many millions of dollars. This is how websites and e-mail services maintain the data that users access when they log in.
Hard drives are also used for archiving information on smaller scales. Many offices, universities and scientific institutions back up data on centrally located hard drives in case it is lost on an individual's computer. Routine backups are part of many networks.

Data Transfer

In recent years small, portable hard drives known as "mobile HDDs" have become common. These make the transfer of large amounts of data possible by allowing users to simply transport the hard drive from one computer to another where it can be copied to the computer's internal hard drive or accessed from the portable hard drive itself. Some portable hard drives consume a small enough level of power to allow them to be powered through their USB connection, which is also their means of connecting to the computer. Such devices are known as "bus powered."
Other external hard drives, especially those involved in the transmission of especially large amounts of data, may connect to a computer through an IEEE 1394 interface, also known as a "firewire" connection. Such high-speed connections can make the performance of an external hard drive nearly as responsive as that of an internal drive that is connected directly to the motherboard.

Hard Drives in Other Devices

One of the major trends in hard drives in recent years involves the integration of hard drives into all manner of electronic devices. Portable music players rarely use traditional recording media and instead store their music, pictures and other data on hard drives. Cell phones also use hard drives to store phone numbers, call data, music, pictures and their operating systems. Both portable music players and cell phones (and devices that combine both) are regularly marketed with attention paid to the size of their hard drive.
New applications for hard drives include cars, where in-dash hard drives allow drivers to load navigation systems and maps, store their music digitally in their car's computer and store custom settings for any of a car's electronic systems.

References

• Storage Review: Hard Disk Drives
• Hard Drives: How They Work

Resources

• Cnet: Hard Drive Reviews