On Availability QoS for Replicated Multimedia Service and Content
Key: OSS02-1
Author: Giwon On, Jens Schmitt, Ralf Steinmetz
Date: November 2002
Kind: In proceedings
Publisher: Springer LNCS 2515
Book title: Proceedings of International Workshop on Interactive Distributed Multimedia Systems 2002 (IDMS-PROMS02), Coimbra, Portugal
Abstract: Recently, it has been realized that the importance of satisfying service availability is becoming one of the most critical factors for the success of Internet-based services and applications. In this paper, we take an availability-centric view on QoS and focus on the issues of providing availability guarantees for distributed and replicated multimedia services and contents. For this purpose, we develop a concept called quality of availability (QoA) in which the availability is treated as a new controllable QoS parameter. We especially tackle the replica placement (RP) problem and study the effects of number and location of replicas on the achieved availability. We decompose the RP problem into three sub-problems: (1) finding a "good" placement for a fixed number of replicas, (2) checking the reached QoA with a selected replica placement, and (3) determining the number and location of replicas for satisfying a requiredQoA. For each RP sub-problem, we review existing related work for algorithms ranging from heuristic to exact methods as well as devise new algorithms where existing work is lacking and evaluate their achieved QoA. Based on a simulation study, we find that (1) the location of replica is a more relevant factor than their number for satisfying the QoA requirements by different users, and (2) the heuristic methods, in general, cannot give any guarantee for their achieved QoA, even though they are very efficient for large size graphs. Our proposed QoA concept and model can be used as a base mechanism for further study on the availability and reliability QoS for dynamically changing network service environments.
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