Dynamic cache reconfiguration strategies for cluster-based streaming proxy

The high bandwidth and the relatively long-lived characteristics of digital video are key limiting factors in the wide-spread usage of streaming content over the Internet. The problem is further complicated by the fact that video popularity changes over time. In this paper, we study caching issues for a cluster-based streaming proxy in the face of changing video popularity. We show that the cache placement problem for a given video popularity is NP-complete, and propose a series of techniques to address the problem. We first introduce the dynamic first fit (DFF) algorithm that give the results close to the optimal cache placement (OCP). We then propose minimum weight perfect matching (MWPM) and swapping-based techniques that can dynamically reconfigure the cache placement to adapt to changing video popularity with minimum copying overhead. Our simulation results show that MWPM reconfiguration can reduce the copying overhead by a factor of more than two, and that swapping-based reconfiguration can further reduce the copying overhead compared to MWPM, and allow for the tradeoffs between the reconfiguration copying overhead and the proxy bandwidth utilization.