Disk Storage Devices

Disk drives of various kinds are used to store and transfer data files. When data is enterd into a computer it must be saved as a file to preserve it when the computer is switched off: Also software applications need to install files on the main disk drive in the computer in order to run.

The most important type of drivein the computer is the hard disk which is used to store the software and data on which the computer run.

Most computers will also have removable disk drives to install software and backup data files.

Disk performance is principally a question of capacity: how much data can be stored on the disk?
Other factors that influence disk performance are the seek time and the transfer rate.

Hard Disk

The hard disk is usually a device fixed inside the computer. It stores large volumes of data which can be accessed and retrived quickly. The seek time of a hard disk is much lower and the transfer rate much higher than any other type of disk drive.

• Hard disk consist of a number of rigid magnetic disks in a protectives casing. Data is recorded magnetically onto concentric circular tracks each one divides into a number of sectors. Data is accessed by an arm moving over the surface of the disk.

• Hard disk can hold very large amounts of data and are usually very fast in comparison with other storage devices. They very considerably in terms of piece depending on their speed and capacity. Hard disk on sale at the time of writing very in capacity from 80 GB to 750 GB.

• When  you install software the setup istructions indicate the amount of free disk space required for the software to run effectively. Applications typically take up 50-200 MB each though multimedia applications and games can require far more.

• Most hard disk are fixed inside the computer. Removable hard disk are available but tend to be much more expensive.