Hardware related data loss
When the storage media itself has incurred physical damage, the result is usually devastating, and most often, recovery is costly.
Optical Discs
Scratched Off Recording Dye
A good example of unrecoverable data loss is optical discs which have their storage plastic or dye scratched off. Once the material is scratched off, your data is permanently lost since that is where data is stored.
Scratched Disc
Scratched discs however, present another problem. The data may still be on the disc, BUT since there are scratches present on the polycarbonate plastic, a disc drive will have problems reading the disc. Since the reading mechanism is very precise, scratches affect the reading process, and result in reading failure, even though data is still stored on the disc.
