Disk Drives

Disk Drives and Data Storage

While Random Access Memory (RAM) provides fast, temporary storage for data and running programs, it is volatile—meaning all stored information is lost when the computer is turned off or restarted. To retain data permanently, it must be saved to a non-volatile storage device, most commonly a disk drive. Disk drives serve as the main long-term storage solution in a personal computer (PC), storing the operating system, software applications, user data, and system files.

A disk drive can refer to various types of storage devices, including hard disk drives (HDDs) and solid-state drives (SSDs), though this description primarily applies to traditional magnetic hard drives. These drives store data magnetically on a spinning platter. The surface of the platter is coated with a magnetic material, and data is written to and read from it using a moving read/write head.

To organize and manage the data, the storage space on a disk drive can be divided into logical areas called directories, or more commonly referred to as folders. These directories help users and the operating system sort and access files in a structured and intuitive manner.

The data on a magnetic disk is recorded in the form of tiny magnetic fields. These fields are aligned to represent binary data—0s and 1s. As the disk spins, data is written onto the surface in concentric circles known as tracks. Each track is further divided into smaller units called sectors, which are uniform in size and represent the smallest accessible storage unit on the disk. Each sector and track is assigned a unique identification number, enabling the computer to locate and retrieve specific pieces of data efficiently.

This system of tracks and sectors ensures that the computer can store and access large volumes of data quickly and with a high degree of accuracy. When you save a file, the operating system keeps track of which sectors the data is stored in, so it can be read back in full when needed.