Sunday, June 20, 2010

796 acres of data

I just bought a new computer (haven’t had a chance to open the box yet, actually). As an accessory, I got a backup disk drive, a device about the size of your average hardcover novel. This drive cost less than $200 and hold 2TB of data. That two terabytes. Two trillion bytes.

So I thought about the first disk drive, the IBM 350, which held five million 7-bit characters and was able to access any record in an average of 800 ms (that’s eight tenths of a second, which is longer than it takes some people to tie their shoes).

The 350, as you can see from the Wikipedia picture, was the size of a side-by-side refrigerator and needed five feet of clear floor space around it. If you were to arrange units in a rectangular grid, I figure each unit would occupy about 65 square feet. It would take 533 IBM 350s to hold 2TB of data, and that means you would need close to thirty-five million square feet of space, about 796 acres of air-conditioned floor space. I suppose you could house them in, say, forty-story buildings, reducing the footprint from 796 acres to about forty acres (buildings need space around them). Then there’s the power requirement. And then there’s the question of how much longer than 800 ms it would take to retrieve the data.

Okay, that’s unfair
Let’s skip ahead to the first IBM disk unit I actually saw, in 1962. That was an IBM 1301. The model 2 stored fifty-six million characters and had slightly faster access times (100 to 800ms). But it had the same footprint as the 350, so now we’re down to seventy-two acres.

And what did that seventy-two acres of data cost?
You could have leased it all (exclusive of the real estate and without accounting for the cost of electricity to run and cool the units) a mere $168,000 a month. Or you could have bought the ball of wax for $8.9 million.

Now let’s talk about how the cost of doing business has risen.

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