Analysis of Load Balancing Issues Caused by Intra-Movie Skewness for Parallel Video Servers

Abstract

Parallel video servers divide movies into segments and put them across multiple nodes, which avoid load imbalance problem caused by movie popularity. However, due to users' various viewing time, the retrieval rates of movie segments are quite different, and some segments are more popular than others. This instance is called intra-movie skewness, which probably leads to load imbalance among the nodes in parallel video servers.

In this paper we first study intra-movie skewness through a trace-based analysis. It is proved that this skewness results in serious performance degradation of the video server with traditional round robin data placement. Then, according to the characteristics of intra-movie skewness, we propose a strategy, Symmetrical Pair Scheme to introduce our symmetrical data placement style, which has better load-balancing performance. Moreover, based on Symmetrical Pair Scheme we present a novel method, Symmetrical Replication Pair Scheme. Our analysis result shows that it can prevent the impact of intra-movie skewness and bring desirable load-balancing performance to parallel video servers.