Google has kept costs low by using inexpensive, redundant hardware and expecting it to crash

• The technical wizardry behind Google's successful search engine may come down to a blindingly obvious insight: PCs crash.
• On Wednesday, Urs Hoelzle, a vice president of engineering and of operations at the search giant, shed some light on how Google's data centers operate.
• Bottom line: According to Hoelzle, Google has inexpensively built out its computing infrastructure by using thousands of "commodity" servers, instead of fewer high-end, and high-priced, machines.
• The trick is to make these racks of hardware work together and to ensure that the failure of one machine doesn't derail an operation.
• The way Google has been able to build out its computing infrastructure for millions, rather than tens of millions, of dollars is by buying relatively cheap machines.
• Looking at hardware costs, company engineers saw that purchasing a few high-end servers, with eight or more powerful processors, costs significantly more than dozens of simpler "commodity" servers.
• The trick is to make these racks of hardware operate in tandem and to ensure that the failure of one machine does not derail an operation, such as returning a search query or serving up an ad.
• The company wrote its own file system, called Google File System, which is optimized for handling large, 64 megabyte blocks of data.
• Significantly, the file system was designed to assume that a failure, such as a failed disk or unplugged network cable, can happen at any time.
• Google's programming tool, called MapReduce, which automates the task of recovering a program in case of a failure, is critical to keeping the company's costs down.
• In a follow-up interview with CNET News.com, Hoelzle said the cost of power is another important factor in Google's data center designs.