Storage hierarchies: Gaps, cliffs, and trends

Trends in storage from 1952 to 1972 are presented. They include an increasing diversity of storage types, an increase in on-line storage capacity that exceeds the three-orders-of-magnitude increase in computer power, and an increased management of the storage complex by the system. The impact on past and present system design of the access gap between main memory and electro-mechanical storage is discussed. The growing importance of the gap between on-line and off-line storage is also noted. These two gaps represent significant opportunities for innovation in hardware and systems.