Analyzing the file availability and download time in a P2P file sharing system

In this paper we study the performance of P2P file sharing systems. We are especially interested in how the division of the file into chunks as well as the used chunk selection policy influence on two performance metrics, named the availability and mean download time of the file. We propose a detailed Markov chain model that allows estimating the mean lifetime of the system and comparing different chunk selection policies exactly. In addition, we use simulations to evaluate more complex systems. Results suggest that splitting the file from one chunk into two chunks improves the performance of the system significantly. Meanwhile, the superiority of a chunk selection policy depends on many factors, such as the arrival rate of the new downloaders and service time distribution.