Adam Shostack wrote:
Could you give me a cost estimate for keeping video of the last 10 minutes of 250 million lives? This is essentially one of Brin's suggestions, and it strikes me as astoundingly pricey, even if you just consider the cost of cameras, fiber, switches, and vcrs, and ignore the problem of deciding what tape to keep.
Some back of the envelope leads me to over a trillion, figuring that a second of video takes 10kb, and disk costs about $50/mb. 250m cameras at $40 each, fiber connections at $400 each, etc.
That's 50 CENTS per megabyte, but actually it is twice less than that. My calculation (storage costs only, assume 10kb/sec/person): 6000KB * 0.25c/MB * 2.5E8 = 375 million. Good money, but not even close to your number. Also, storing data on optical disks is about $20/600MB, which is only three cents per megabyte -- ten times less than above. Even though this is storage media cost alone, 37.5 million surely sounds like a reasonable number -- it is 15 cents per person, or 90 cents per hour, or $22.6 per day per person. A little steep, but after several years this cost may decline tenfold. Of course my rough calculation missed a lot of important expenses. - Igor.