Tower Of Power    Feb. 11, 2002
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Balancing workloads among dozens, even hundreds, of servers supporting a distributed very large database will present significant programming and system-configuration challenges because of the volumes of data and the number of servers involved. In November, Florida International University in Miami went live with a 20-terabyte database of high-resolution aerial and satellite images of the entire United States provided by the U.S. Geological Survey. The system is believed to be the largest publicly accessible database on the Internet. But data for individual images is distributed to avoid overloading any single server in the event of a spike in demand for a particular image--say, as the result of a natural disaster. To maintain the database's performance, the school is creating a hierarchy of data caches to hold more frequently accessed images. The caches should reduce the primary database's workload.