Critical assessments of optical and HDD recordings

Data storage technologies such as HDD and optical recordings are key to the information-oriented society, and the demand for their technological developments will be undoubtedly more strongly increasing. For mass-data storage applications, the capacity or areal density of drives will be more demanded. With increasing areal density, both track pitch and bit-length must be decreased. Yet, serious issues remain to be solved before any drives will be commercially available. These issues are discussed.