Web Scale applications are characterized by high concurrency, a requirement for short response times, and highly variable throughput demands on the underlying infrastructure.
The picture at left shows a typical situation faced by a web scale application (click on the picture to see a larger image). A steady state throughput on the system is a hundred or so events per minute. About ten hours into the measurement period, some external event caused a sudden increase in the system throughput demands. The short term average workload rose by approximately one order of magnitude, and this kind of variability is not an aberration; it is a fact of life in the Web Scale Application. [...]