Cluster System Capacity Improvement by Transferring Load in Virtual Node Distance Order

Shigero SASAKI
Atsuhiro TANAKA

IEICE TRANSACTIONS on Information and Systems   Vol.E92-D    No.1    pp.1-9
Publication Date: 2009/01/01
Online ISSN: 1745-1361
DOI: 10.1587/transinf.E92.D.1
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Computer Systems
load balancing,  herd effect,  request departures,  cluster systems,  

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Cluster systems are prevalent infrastructures for offering e-services because of their cost-effectiveness. The objective of our research is to enhance their cost-effectiveness by reducing the minimum number of nodes to meet a given target performance. To achieve the objective, we propose a load balancing algorithm, the Nearest Underloaded algorithm (N algorithm). The N algorithm aims at quick solution of load imbalance caused by request departures while also preventing herd effect. The performance index in our evaluation is the xth percentile capacity which we define based on throughputs and the xth percentile response times. We measured the capacity of 8- to 16-node cluster systems under the N algorithm and existing Least-Loaded (LL) algorithms, which dispatch or transfer requests to the least-loaded node. We found that the N algorithm could achieve larger capacity or could achieve the target capacity with fewer nodes than LL algorithms could.