Throughout modern history many and various digital storage systems have been researched, developed, manufactured, and eventually surpassed in an effort to address ever-increasing demands for density, operating speed, low latency, endurance, and economy[1]. This cycle of innovation has lead us to a new generation of NAND Flash memory-based solid state drives (SSDs) that represent the next evolutionary step in both enterprise and consumer storage applications.

This article surveys the memory storage landscape of the past 50 years—starting at the beginning of digital storage and paying homage to IBM’s groundbreaking RAMAC disk storage unit and StorageTek’s DRAM-based SSD; then enumerating the benefits of modern NAND Flash memory and advanced SSDs; and finally looking forward to the near-future possibilities of nonvolatile storage.

Introduction: The Need to Store Data

Since men first scribbled on cave walls, humanity has

Table 1: Digital Storage Time Line

recognized the intrinsic value of information and has employed a variety of ways and means to safely store it. The ability to reference numbers for calculation or to review information for planning, learning, and action is fundamental since “all computations, either mental, mechanical, or electronic require a storage system of some kind, whether the numbers be written on paper, remembered in our brain, counted on the mechanical devices of a gear, punched as holes in paper, or translated into electronic circuitry.”[2]

In day-to-day life, this fundamental need to store data generates innumerable documents, spreadsheets, files, e-mails, and trillions of other work-related bytes all stored on disks around the globe. Add to this commercial data the billions of photographs, songs, videos, and other personal information or files saved every day, and it is little wonder that the storage industry has seen an unprecedented boon of late. This boon will ultimately transform storage along an evolutional path toward better performance, greater density, and higher reliability. It will make storage a system rather than a subsystem [3]. To best understand where an industry is headed, often we must look to where it’s been.

Notes

[1] J.P. Eckert, Jr., “A Survey of Digital Computer Memory Systems,” Proceedings of the Institute of Radio Engineers (A Progenitor of the IEEE) (October 1953): page 1993 downloaded from ieee.org on October 10, 2008.
[2] Gamze Zeytinci, “Evolution of the Major Computer Storage Devices: From Early Mechanical Systems to Optical Storage Technology,” (Spring 2001): page 4 downloaded from http://www.computinghistorymuseum.org/teaching/papers/research/StorageDevices-Zeytinci.pdf on October 11, 2008.
[3] Richard L. Villars, “IDC’s Enterprise Disk Storage Consumption Model: Analytics and Content Depots Provide a New Perspective on the Future of Storage Solutions,” IDC (September 2008): pages 1 to 3.