Just got back from Chicago, where over the past 2 days a small group of scientists, academia and industry discussed various aspects of cloud computing and related topics.
One of the topics was about comparing extreme large scale analytical problems and the systems leverage to solve them. In order to compare classes of super computers, Alex Szalay (John Hopkins University) explained a simple yet interesting figure: The AMDAHL number (Amdahl's Law Bell, Gray and Szalay 2006)
Alex explained the Amdahl number (BW) as One bit of IO/sec per instruction/sec.
Why is this figure interesting? To compare the analytical capabilities of various extreme large clusters, it is important to categorize them into different groups based on their processing capabilities. Typical commercial applications of large scale analytics require large amounts of IO per available CPU while various scientific applications require less IO per available CPU.
For a Blue Gene the BW=0.013, the JHU cluster BW = 0.664. So off