The facility in The Dalles is only the latest and most advanced of about two dozen Google data centers, which stretch from Silicon Valley to Dublin. All told, it's a staggering collection of hardware, whose constituent servers number 450,000, according to the lowest estimate.
The extended Googleplex comprises an estimated 200 petabytes of hard disk storage – enough to copy the Net's entire sprawling cornucopia dozens of times – and four petabytes of RAM. To handle the current load of 100 million queries a day, its collective input-output bandwidth must be in the neighborhood of 3 petabits per second.
The recent explosion of hard disk storage capacity makes Moore's law look like a cockroach race. In 1991, a 100-megabyte drive cost $500, and a 50-megahertz Intel 486 processor cost about the same. In 2006, $500 buys a 750-gigabyte drive or a 3-gigahertz processor. Over 15 years, that's an advance of 7,500 times for the hard drive and 60 times for the processor. By this crude metric, the cost-effectiveness of hard drives grew 125 times faster than that of processors.
Much more in the original article.