Foreword

My experience with storage began in the early 1960s when I was a lab technician at the University of California. I spent late nights operating an IBM 704 computer, processing data from Bevatron bubble chamber experiments and storing it onto IBM 727 tape drives. Registers were manually set through an octal keyboard; programs and data were loaded through a punched card reader; and I was the operating system, loading card decks, mounting and dialing in the tapes drives, and servicing the output printers. The 1960s were a period of social and political unrest on the Berkeley campus, and I ended up leaving the university to join the military service, far removed from storage technology.

After five years, I left the military to seek a career in the computer industry. I applied at IBM, hoping to leverage the computer experience from my university days. During my first interview, I was asked what I knew about DASD. I was stunned. In a relatively short span of five years, the world I knew of punched cards, tape storage devices, and printed output was replaced by something called a direct-access storage device. This was my introduction to disk drives. I felt like Rip Van Winkle, who awoke from a 20-year sleep to find the world completely changed. Ever since then, I often wondered if this type of transformation would occur again, and I would wake up one day to find an entirely new world of storage.

In the 40 some years since my introduction to disk storage, I worked for IBM and then for Hitachi Data Systems in the storage industry and witnessed the transformation of storage to where it is today. This transformation did not occur overnight. It happened year after year, and the transformation continues to move forward. While the primary data storage device continues to be a mechanical device that records data as magnetic bits on a rotating disk platter, a tremendous amount of technology has been developed to increase recording densities from 2,000 bits per in² to 10¹² bits per in² (2 Kb/in² to 1 Tb/in²). In the last few years, solid-state disks based on flash technology were introduced for high-performance storage requirements. While SSDs were initially 10 times the cost per bit of high-performance hard disks, the price gap is closing as the cost of SSDs is declining faster than hard disk prices.

IT is going through a major transformation today as the confluence of Big Data, cloud computing, social networks, and mobile devices change the way we work with and process information. These changes are driving an accelerating need for more storage. This need for storage goes beyond performance and capacity. It requires technologies to make the storage of data more efficient, more reliable, more available, and simpler to manage, procure, protect, secure, search, replicate, and access as blocks, files, or objects. Storage is much more than the media that holds the data bits.

This book helps the reader understand these requirements for the storage of data today, including the latest storage technologies and how they work together. This is a reference manual for IT professionals who need to make informed decisions in the investment of storage choices.

Hu Yoshida

Vice President and Chief Technical Officer

Hitachi Data Systems