The term "disk-to-disk", or "D2D", generally refers to disk-to-disk backup. With D2D, a computer hard disk is backed up to another hard disk rather than to a tape or floppy.
D2D is often confused with Virtual Tape, but differs in that it enables multiple backup and recovery operations to simultaneously access the disk directly by using a true file system.
The Typical advantages of disk-to-disk are
(1) Higher speed and higher capacity, relative to tape or floppy, resulting in shorter backup and recovery windows.
(2) Non-linear recovery of data, enabling a specific file to be restored quicker and simpler than with tape.
(3) Lower total cost of ownership due to increased automation and lower hardware costs.
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