A
disk image contains the complete structure of a storage device or piece of storage media, such as a hard disk or CD. In simple terms, a disk image is a precise digital replica of a disk in which all data is stored as a single type of file (an image) to preserve the context and integrity of the data on the drive. Disk images are exact binary copies of a storage disk, and contain all files and folders as well as boot sectors, volume attributes and other system data. Because it includes only raw binary data, a complete disk image can be made of any drive, partition or logical disk, regardless of operating system or format.
Disk images are most often made for
backup and restore purposes, so that data can be recovered in the event of accidental deletion, logical corruption, and hardware damage or failure.
Backup and restore software usually features the ability to create a disk image that updates incrementally according to the establishment of recovery points, so that the entire drive or volume does not need to be re-written to secondary storage but instead only changes are copied after an initial backup.
Having a backup of a properly configured system is critical to
resuming business operations following a disaster that results in a loss of hardware or software. A disk image is rapidly deployed compared to manually-installed and configured programs and settings, reducing recovery times significantly.
Due to the raw format of a disk image, however, backup systems which write the secondary data for restore must be extremely fault-tolerant. Backup providers such as CRC DataProtection employ systems that detect and repair logical inconsistencies and duplicate files in a self-healing fashion as backups are conducted. In this way, disk-to-disk backup of of a disk image can resume automatically following an interruption without compromising the integrity of the disk image.
