For example, Google designed a software system it calls the Google File System that keeps copies of data in several places so Google does not have to worry when one of its cheap servers fails. This approach also means that it does not have to make regular backup copies of its data as other companies do.
Another system, called the Google Work Queue, allows a big pool of servers to be assigned to various tasks as needed and reassigned to other projects later. This concept, called "virtualization," has become a trend among large data center operators, which also want to reduce the expense of having separate servers dedicated to each system. But most companies buy commercial software to track which computers are doing what, a complex process.