Disk image
- Snippet from Wikipedia: Disk image
A disk image is a snapshot of a storage device's content – typically stored in a file on another storage device.
Traditionally, a disk image was relatively large because it was a bit-by-bit copy of every storage location of a device (i.e. every sector of a hard disk drive), but it is now common to only store allocated data to reduce storage space. Compression and deduplication are commonly used to further reduce the size of image files.
Disk imaging is performed for a variety of purposes including digital forensics, cloud computing, system administration, backup, and emulation for digital preservation strategy. Despite the benefits, storage costs can be high, management can be difficult and imaging can be time consuming.
Disk images can be made in a variety of formats depending on the purpose. Virtual disk images (such as VHD and VMDK) are intended to be used for cloud computing, ISO images are intended to emulate optical media, such as a CD-ROM. Raw disk images are used for forensic purposes. Proprietary formats are typically used by disk imaging software.