Optical, Magnetic and Solid state
The Optical Storage is a device that has a laser to read the data off a Disc or a Blueray. The Data is marked on the Disc which is read by a light (often a laser). Optical storage can range from a single drive reading a single CD-ROM to multiple drives reading multiple discs such as an Optical jukebox. Single CD's can hold around 700MB and Optical jukebox can hold much more data.
The Magnetic Storage receives a magnetism pulse that transfers it into data