A Rank Based Replacement Policy for Multimedia Server Cache Using Zipf-Like Law

The cache replacement algorithm plays an important role in the overall performance of Proxy-Server system. In this paper we have proposed VoD cache memory replacement algorithm for a multimedia server system. We propose a Rank based cache replacement policy to manage the cache space in individual proxy server cache. Proposed replacement strategy incorporates in a simple way the most important characteristics of the video and its accesses such as its size, access frequency, recentness of the last access and the cost incurred while transferring the requested video from the server to the proxy. We compare our algorithm with some popular cache replacement algorithm using simulation. The video objects are ranked based on the access trend by considering the factors such as size, frequency and cost. Many studies have demonstrated that Zipf's-like law can govern many features of the VoD and is used to describe the popularity of the video. In this paper, we have designed a model, which ranks the video on the basis of its popularity using the Zipf-like law. The video with higher ranking is named "hot", while the video with lower ranking is named "cold". The result show that the proposed rank based algorithm improves cache hit ratio, cache byte ratio and average request latencies compared to other algorithms. Our experimental results indicate that Rank based cache replacement algorithm outperforms LRU, LFU and Greedy Dual

Theoretical study of cache syatems

The aim of this paper is a theoretical study of a cache system in order to optimize proxy cache systems and to modernize construction principles including prefetching schemes. Two types of correlations, Zipf-like distribution and normalizing conditions, play a role of the fundamental laws. A corresponding system of equations allows to describe the basic effects like ratio between construction parts, steady-state performance, optimal size, long-term prefetching, etc. A modification of the fundamental laws leads to the description of new effects of documents' renewal in the global network. An internet traffic caching system based on Zipf-like distribution (ZBS) is invented. The additional module to the cache construction gives an effective prefetching by lifetime.Comment: 17 pages, 5 figures, 1 tables. submitted to Ther. Com. Sc.

On the universality of rank distributions of website popularity

We present an extensive analysis of long-term statistics of the queries to websites using logs collected on several web caches in Russian academic networks and on US IRCache caches. We check the sensitivity of the statistics to several parameters: (1) duration of data collection, (2) geographical location of the cache server collecting data, and (3) the year of data collection. We propose a two-parameter modification of the Zipf law and interpret the parameters. We find that the rank distribution of websites is stable when approximated by the modified Zipf law. We suggest that website popularity may be a universal property of Internet.Comment: 6 pages with 5 figures, IEEEtran.cls, paper substantially rewritten, new figure and tables adde