Optimal Capacity Allocation for Web Systems with End-to-end Delay Guarantees

Providing quality of service guarantees have become a critical issue during the rapid
expansion of the e-Commerce area. We consider the problem of .nding the optimal
capacity allocation in a clusteredWeb system environment so as to minimize the cost
while providing the end-to-end performance guarantees. In particular, we consider
constraints on both the average and the tail distribution of the end-to-end response
times. We formulate the problem as a nonlinear program to minimize a convex
separable function of the capacity assignment vector. We show that under the mean
response time guarantees alone, the solution has a nice geometric interpretation.
Various methods to solve the problem are presented in detail. For the problem
with tail distribution guarantees, we develop an approximation method to solve the
problem.We also derive bounds and show that the solution is asymptotically optimal
when the service requirement becomes stringent. Numerical results are presented to
further demonstrate the robustness of our solutions under data uncertainty.

By: Wuqin Lin; Zhen Liu; Cathy H. Xia; Li Zhang

Published in: RC23650 in 2005


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