chapter  17

The RAID Advantage

WithTyson Heyn

Electronic data processing evolved from virtually nothing 50 years ago to its virtual omnipresence in the industrialized societies of the world today. Digitized information, or data, is being used to enable everything from live conversations between continents via satellite to the advancement of scientific discoveries and research, to controlling the temperatures of different rooms in a home. Hard disk storage plays an important role in enabling improvements to networked systems, because the vast and growing ocean of data has to reside somewhere. The solution to providing access to many gigabytes of data to users fast and reliably has been to assemble a number of drives in a gang or array of disks. These are known as redundant arrays of independent disks (RAID) subsystems. RAID subsystems can be optimized for performance, the highest capacity, fault tolerance, or a combination of two or three of the above. Different so-called RAID levels have been defined and standardized in accordance with those general optimization parameters.