With the rapid development of network technology, the growth of many network applications are also vigorous. Content delivery systems are widely used and considered as the killer applications, such as file sharing, content delivery of set-top box, video-on-demand system and etc. This thesis proposes a robust, scalable, highly available and load-balanced distributed content delivery system. The proposed system contains a proven Adaptive Quality of Service (AQoS) algorithm in order to provide differential service. In our experiment, it shows that the system load which only serves low class users is stable even when many users are served and the storage throughput is used up. It is the important characteristic especially in large-scale environment which generally has some high class users and over crowd of low class users. Moreover, the proposed system has passed the severe examination of business environment which needs to not only serve tens of thousands of users concurrently but also provides many enterprise features such as robustness, scalability, high available and load balance in order to ensure 24-hour operation night and day. The proposed system can be used flexibly in large, medium and small-scale environment. In addition, some algorithms have also been developed to increase overall system performance and fault tolerance. Finally, the system also provides a comprehensive monitoring and alarm system which could immediately reflect current situation and performance of system. Therefore, administrators can control the system according to its policy and users can have a robust, scalable and highly available content delivery system.

隨著網路技術的蓬勃發展，網路上許多應用服務也隨之蓬勃發展。其中內容派送系統的服務更是隨處可見，舉凡檔案分享、機上盒內容派送、隨選視訊系統等。在此篇論文中，提出了一個分散式的內容派送系統並著重於伺服器端架構的設計，提供具有差異性服務、穩定、負載均衡、擴充性高的系統。我們發展出一套經過驗證的 AQoS 的演算法提供差異性服務。從論文的實驗結果中可看到，在大量使用者且儲存設備的資源幾乎消耗殆盡的情況下，服務低速使用者伺服器的負載幾乎沒有增加，呈現穩定的狀態。這是本系統一個很重要的特徵，尤其在一般提供差異性服務的內容派送系統中，少數的高速使用者及大量的低速使用者是非常常見的狀況。特別是在大規模的環境下，系統負載仍不受大量低速使用者的影響是本系統一個很重要的特色。尤有甚者，本論文所提出之系統架構也通過了實際的線上商業系統的嚴格考驗，該商業系統不僅同時需要服務上萬的使用者也要本系統提供像是穩定、負載均衡、擴充性高、高可用性及錯誤容忍等企業所需的功能以提供其二十四小時不間斷的服務。本論文提出的系統可彈性的應用在大、中、小不同規模的環境中。除此之外，本論文也提出一些演算法用以增加整體系統運作效能及容錯能力。最後，系統還提供一套完善的監控與警報機制，可即時反應出當前狀況與效能表現。因此，透過本論文提出的系統架構，管理者可根據其政策調控系統中內容維護方式，而使用者可獲得具備差異性服務、穩定、可靠的內容派送服務。

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