一個有效促進網際網路伺服器之負載平衡的工作分配方法

Abstract

一個有效促進網際網路伺服器之負載平衡的工作分配方法 研究生: 楊正仁 指導教授：陳正教授 國立交通大學資訊工程系碩士班 摘 要 近來，網際網路的蓬勃發展己使得許多網路上的應用，如電子商務、網路股票交易系統，廣為流行及被人們所依賴。然而，欲提供這些應用，需要有一個高效能的網際網路伺服器系統支援。在這篇論文中，我們提出一個有效促進負載平衡的工作分配方法，名為具有內容調節的機率分配方法。這個方法是以使用者需要的資料做為工作分配的基本考慮條件。根據預測的資料熱門度來做複製份數的適當調整，再用我們的資料擺放方法把這些資料放在各個伺服器中，並以儲存在工作分配者中相關的資料分佈記錄，做為工作分配的依據，最後為了避免突來的需求量使得伺服器負載過重，伺服器可改以品質較差的內容來回應使用者需求。它可提供各個伺服器的負載平衡，也可以保證伺服器在使用者過多時仍有一定的服務品質(QoS)。經由我們初步模擬評估結果顯示，我們的方法的確較其他的方法有較高的效能，尤其是在使用者過多的情況下更有較好的表現。有關此方法詳細的設計原理及效能評估將會在論文以後的章節中一一介紹。

An Effective Request Distribution Mechanism For Improving Load Balance in Web Server System Student: Cheng Zen Yang Advisor: Prof. Cheng Chen Institute of Computer Science and Information Engineering National Chiao Tung University Abstract Recently, rapid developments of Internet make several network applications, such as E-commerce and stock trading, more popular and thus change human life. However, these services have to be supported by a high performance web server system. In this thesis, we will propose an effective request distribution mechanism for improving load balance in web server system, called Probabilistic Dispatching with Content Adapted (PDCA) method. The request distribution of this method is determined based on requested documents. Using predicted document popularity to adjust the number of replicas, we place the documents among servers by our data placement scheme. The dispatcher distributes a request according to dispatching probability of the requested document. Furthermore, in order to reduce the impacts on burst traffic, servers may transmit adapted documents to requests. This method can support load balance and ensure QoS of overloaded servers. According to preliminary performance evaluations, we have found that our method is superior to other schemes especially for massive traffic. The detailed information about design concept and performance evaluations will be described in the literature.