What is "disk image"

alt. (context computing English) A copy of all or part of a disk drive retained for backup or replication purposes. n. (context computing English) A copy of all or part of a disk drive retained for backup or replication purposes.

Disk images, in computing, are computer files containing the contents and structure of a disk volume or an entire data storage device, such as a hard disk drive, tape drive, floppy disk, optical disc or USB flash drive. A disk image is usually made by creating a sector-by-sector copy of the source medium, thereby perfectly replicating the structure and contents of a storage device independent of the file system. Depending on the disk image format, a disk image may span one or more computer files.

Disk image file formats may be open standards, such as the ISO image format for optical disc images, or proprietary to particular software applications.

As disk images contain the contents of entire disks, they can be huge. Some disk imaging utilities are filesystem-aware and can omit copying unused space from the source media, or compress the disk they represent to reduce storage requirements.