劉邦鋒臺灣大學：資訊工程學研究所王相凱Wang, Hsiang-KaiHsiang-KaiWang2007-11-262018-07-052007-11-262018-07-052006http://ntur.lib.ntu.edu.tw//handle/246246/53860此篇論文討論在考量QoS限制的情況下，擺放檔案複本達到系統最佳化的問題。雖然已經有許多關於複本放置的研究工作，但是其中大部分的研究都是考量系統的整體效能，而忽略掉個別伺服器的差異，所以可能會導致部分使用者的不便。而在異質的網路環境，這種差異性更加明顯，這個問題也越顯重要。我們提出一個新的近似演算法來解決這個問題，經由實驗，我們證實了我們提出的演算法的確是一個有效率的演算法，並且能夠得到一個與最佳解近似的放置方法。This paper studies the QoS-aware replica placement problem. Although there has been much work on replica placement problem, most of them concerns average system performance and ignores quality assurance issue. Quality assurance is very important, especially in heterogeneous environments. We propose a new heuristic algorithm that determines the positions of replicas in order to satisfy the quality requirements imposed by data requests. The experimental results indicate that the proposed algorithm finds a near-optimal solution effectively and efficiently. Our algorithm can also adapt to various parallel and distributed environments.1. Introduction p.5 2. Related Work p.7 3. System Model p.10 3.1 Service Quality Requirement p.12 4. Heuristic Algorithms p.13 4.1 Implementation p.16 4.2 Time Complexity p.17 5. Performance Evaluation p.18 5.1 The effects of QoS p.19 5.2 The effects of alpha p.21 5.3 Execution time p.23 6. Conclusion p.25en-US品質複本QoSreplicationreplicathesis