The other day I wrote about Google’s technology cost, leading to an estimate of 0.5 dollarcents per delivered search result. There appeared to be a real contrast with the numbers Jim Gray was coming up with from his experience with the Terraserver. I interviewed him to dive deeper into these numbers and their composition. According to Jim, in October 2004 Terraserver was able to serve up to 3 million web pages per day (about 35 per second), each containing quite a bit of graphics. The total operating cost (excluding application development) was $ 387.000 per year.

A Terraserver webpage thus cost 350 microdollars (about 4 hundredths of a cent) to deliver. This is an order of magnitude less than Google’s, and we are not finished. According to Jim Gray, if he would scale up the Terraserver capacity by a factor of 100, getting it in the ballpark of Google, that cost would be even less. In the following table I have summarised the scale factors.

Most services and capital expenditure scale linear with the number of delivered pages, but the management of the hosting and the application do not need to be scaled up. The bottom line is a page cost that dives to 64 microdollars.

As a comparison, a friend of mine runs a simple database driven website on a shared hosting account. The yearly hosting cost is around $ 374, and it serves about 600.000 pages per month, resulting in a page cost of 51 microdollars.

What can explain the difference of a factor of 100 between these page costs, and Google’s? One hypothesis is that, in addition to serving up pages, Google spiders the web. However Terraserver also brings in Terabytes of geographical data every year. So, either Google spends a lot more machine cycles on search results than Terraserver, or most Google hardware is not dedicated to search. Tune in next week, and maybe I’ll have some more data.

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