網際網路的普及化讓許多全球性的跨單位合作計畫變得可行。在這些合作計畫中，都需要一個檔案存放系統來交換資料。這個檔案存放系統必須有高成長性且可以有效的聚集各單位所貢獻的資源。本篇論文提出Collaborative File Repository (CFR)，一個為大型跨單位計劃所設計的檔案儲存系統。CFR使用同儕技術讓系統有高成長性、高效能且方便管理。CFR將各單位貢獻的儲存節點依據地理區域做分類。存在CFR中的所有檔案都會被複製到所有的區域，熱門的檔案也會在區域內做更進一步的複製。這種作法將網路連線侷限在區域範圍內以提昇傳輸效率。CFR系統的維護程序可對應到Coupon Collection Problem，我們也提出一個該問題的最佳解使得系統維護的負擔可最小化。實驗結果顯示CFR可以在少量的複製下達到高效能。

Due to the high availability of the Internet, many large cross-organizational collaboration projects have emerged. One of the fundamental requirements of these collaboration efforts is a storage system to exchange data. This storage system must be highly scalable and can efficiently aggregate the storage resources contributed by the participating organizations. In this thesis, we propose Collaborative File Repository (CFR), a storage system for large scale collaboration projects. CFR uses peer-to-peer techniques to achieve scalability, efficiency, and ease of management. In CFR, storage nodes contributed by the participating organizations are partitioned according to geographical regions. Files stored in CFR are automatically replicated to all regions. Furthermore, popular files are duplicated to other storage nodes of the same region. By doing so, data transfers between users and storage nodes are confined within their regions and transfer efficiency is enhanced. The system maintenance procedure of CFR can be mapped to the Coupon Collection problem, and we propose an optimal solution to the problem to reduce system maintenance overhead. Experiments show that our replication can achieve high efficiency with a small number of duplicates.

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