Minimization of Download Time Variance in a Distributed VOD System


Anne-Elisabeth Baert
Vincent Boudet
Alain Jean-Marie
Xavier Roche


In this paper, we examine the problem of minimizing the variance of
the download time in a particular Video on Demand System. This VOD
system is based on a Grid Delivery Network which is a hybrid
architecture based on P2P and Grid Computing concepts. In this
system, videos are divided into blocks and replicated on hosts to
decrease the average response time. The purpose of the paper is to
study the impact of the block allocation scheme on the variance of
the download time. We formulate this as an optimization problem,
and show that this problem can be reduced to finding a Steiner
System. We analyze different heuristics to solve it in practice, and
validate through simulation that a random allocation is


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