Analysis of Caching Mechnisms from Sporting Event Web Sites

Caching mechanisms are commonly implemented to improve the user experience as well as the server scalability at popular web sites. With multi-tier, geographically distributed caches, it is often difficult to quantify the benefit provided by each tier of caches. In this paper we present and analyze the design of a web serving architecture that has been successfully used to host a number of recent, popular sporting event web sites with two tiers of caches. Special mechanisms are incorporated in this design that allow us to infer the cache performance at the middle-tier of reverse-proxy caches. Our results demonstrate a very high hit ratio (i.e., around 90%) for the reverse-proxy caches employed in this web serving architecture, which is sustained throughout the day and across all geographical regions being served. This is primarily due to system design mechanisms that allow almost all of the dynamic content to be cached, as well as to a significantly larger locality of reference among the users of sporting event web sites than that found in other web environments. These mechanisms also make it possible for us to separate the true user request patterns at the page level from any additional requests induced by the server architecture and implementation.