Virtual disk and virtual drive
Virtual disk and virtual drive are software components that emulate an actual disk storage.
Virtual disks and virtual drives are common components of virtual machines in hardware virtualization but may be used in actual machines as well.
Operation
A virtual drive is computer program that emulates a an actual disk drive, such an optical disc drive, a floppy disk drive or a hard disk drive. To other programs, a virtual drive looks and behaves like an actual drive.
The virtual disk, however, may be any of the following forms:
- Disk image, a computer file that contain the exact structure of an actual disk
- Logical disk, an array of two or more actual disks that cooperatively act like a single disk
- RAM disk, which stores its data in random-access memory instead of a physical disk
Uses
In hardware virtualization, virtual machines implement virtual drives to emulate the behavior of an actual machine. A virtual machine needs one virtual drive and one disk image to start up. More virtual drives are added as needed.
Virtual optical drives are used in actual computers to transfer the contents of the optical disks onto the hard disk drives. Doing so helps resolve the problem of the short life span of CDs and DVDs and allows taking advantage of the faster data transfer rate of hard disk drives. However, virtual optical drives are also used for software piracy: Early computer games used disc existence verification to ensure licensed use. The StarForce copy protection schemes combat disc virtualization. Other video games, however, have replace online product activation instead.