A clone is a form of disk copy that includes data, structure, and even the contents of unused areas.
Disks contain both user data and overhead information about that data, as well as structural information, such as partition layout and boot information. Areas of the disk not in use are considered “free” and available, though the disk areas they represent typically continue to hold whatever data had been previously written.
A clone is a bit-for-bit copy of all data and free space, including the physical structure and layout.
Characteristics of a clone include:
- Actual layout is copied. Files on the resulting clone will be exactly as fragmented as they were on the original.
- The contents of unused areas, or “free space”, is copied. If files were recoverable or “undeletable” on the original, they will be on the cloned copy as well.
- A clone’s size is directly proportional to the size of the original drive, regardless of how much data is actually stored on that drive.
Cloning is often used in mass production of new systems, as well as in some backup strategies.