From: ichudov@algebra.com (Igor Chudov @ home)
Date: Thu, 28 Nov 1996 23:06:41 -0800 (PST)
To: adam@homeport.org (Adam Shostack)
Subject: Re: Anon
In-Reply-To: <199611290336.WAA23956@homeport.org>
Message-ID: <199611290626.AAA03912@manifold.algebra.com>
MIME-Version: 1.0
Content-Type: text


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.