The term "disk space" is an amount of computer storage space on random-access memory devices, such as on a hard drive, floppy or USB flash drive. Disk space units are commonly measured in large numbers of bytes, such as kilobytes, megabytes, and gigabytes, with each unit 1024 times larger than the previous unit. The term originated in the 1950s, for the storage area on a hard disk drive, which internally had disk-shaped platters to rotate quickly. As storage devices have been created in other shapes, the term "disk space" has still been used to refer to areas of permanent storage on various storage devices. The total disk space can span multiple devices, such as areas on an array of disk drives.
The broader term "storage space" is so widely used that it can be mistaken for property storage, as with items stored in a closet or storage bin. Hence, the term "disk space" has remained in use, even when the storage devices are no longer shaped like disks. When storage of data is not permanent, then the common term "memory space" is often used instead.
- "NT Server and Disk Subsystem Performance", Microsoft.com, 2010, webpage: MS2.