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Terabyte Territory

Brian Hayes

In my hand I hold a metal box, festooned with labels, serial numbers, bar codes and tamperproof seals. Inside the box is everything I have written over the past 10 years—articles, a book, memos, notes, programs, letters, e-mail, shopping lists. And there's still plenty of room left for everything I might hope to write in the next 10 years. For an author, it's a little humbling to see so much of a life's work encompassed in a tin box just big enough for a couple dozen pencils.

The metal box, of course, is a disk drive. And it's not even the latest model. This one is a decade old and has a capacity of 120 megabytes, roughly equivalent to 120 million characters of unformatted text. The new disk that will replace it looks much the same—just a little slimmer and sleeker—but it holds a thousand times as much: 120 gigabytes, or 1.2 X 1011 characters of text. That's room enough not only for everything I've ever written but also for everything I've ever read. Here in the palm of one hand is space for a whole intellectual universe—all the words that enter a human mind in a lifetime of reading.

Disk drives have never been the most glamorous components of computer systems. The spotlight shines instead on silicon integrated circuits, with their extraordinary record of sustained exponential growth, doubling the number of devices on a chip every 18 months. But disks have put on a growth spurt of their own, first matching the pace of semiconductor development and then surpassing it; over the past five years, disk capacity has been doubling every year. Even technological optimists have been taken by surprise. Mechanical contraptions that whir and click, and that have to be assembled piece by piece, are not supposed to overtake the silent, no-moving-parts integrated circuit.

Apart from cheering at the march of progress, there's another reason for taking a closer look at the evolution of the disk drive. Storage capacity is surely going to continue increasing, at least for another decade. Those little gray boxes will hold not just gigabytes but terabytes and someday maybe petabytes. (The very word sounds like a Marx Brothers joke!) We will have at our fingertips an information storehouse the size of a university library. But what will we keep in those vast, bit-strewn corridors, and how will we ever find anything we put there? Whatever the answers, the disk drive is about to emerge from the shadows and transform the way we deal with information in daily life.

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