Disk image

A disk image is a computer file containing the complete contents and structure of a data storage device. The term has been generalized to cover any such file, whether taken from an actual physical storage device or not.

Related Topics:
Computer file - Data storage device

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An ordinary backup only backs up the files it can access; boot information, and files locked by an operating system or being changed at the time, may not be saved. A disk image contains all these, and faithfully replicates the data, so it is commonly used for backing up disks with operating systems, or bootable CD/DVDs.

Related Topics:
Boot - Operating system - Bootable - CD - DVD

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The image is saved as a file, which for a full CD or system disk may be quite large (~10 MB to several GB). This file can be saved onto a hard drive, CD, DVD or other media, for later use.

Related Topics:
MB - GB - Hard drive

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Disk images can either be compressed using some type of compression algorithm like LZW, or uncompressed ("raw"). Images of CD-ROMs most often carry the file name extension .iso, referring to the ISO 9660 file system commonly used on such discs. The .iso format is the most common format for Linux distributions and other online images. Other common CD image formats are .nrg (Nero Burning ROM's proprietary format), and .bin/.cue.

Related Topics:
Compression algorithm - LZW - CD-ROM - Iso - ISO 9660 - Linux distributions - Nero Burning ROM

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