Replacement policies for a proxy cacheLuigi

In this paper we analyse access traces to a Web proxy, looking at statistical parameters to be used in the design of a replacement policy for documents held in the cache. In the rst part of the paper we present a number of properties of the lifetime and statistics of access to documents, derived from two large trace sets coming from very diierent proxies and spanning over time intervals of up to ve months. In the second part of the paper we propose a novel replacement policy, called LRV, which selects for replacement the document with the Lowest Relative Value among those in cache. The value of a document is computed adaptively basing on information readily available to the proxy server. The algorithm has no hardwired constants, and the computations associated with the replacement policy require only a small constant time. We show how LRV outperforms LRU and other policies, and can signiicantly improve the performance of the cache, especially a for small one.