Proportional Replication in Peer-to-Peer Networks

We recently showed for peer-to-peer networks, that having the number of replicas of each object proportional to the request rate for these objects has many per-node advantages. In this paper we complement those results to show that this distribution has network-wide advantages as well. Given these benefits of proportional replication, the next issue is achieving proportional replication in a decentralized manner. We show that local storage management algorithms like LRU automatically achieve near-proportional replication and that the system performance with the replica distribution achieved by LRU is very close to optimal. We also show that the LRU responds to a change in user access pattern quickly (the number of accesses taken to reach the new steady-state replica distribution with LRU is close to the minimum possible with any cache replacement algorithm). Analytical models are provided for computing the steady-state network-wide replica distribution and the transient period for LRU.