Abstract. Due to the high availability of the Internet, many large crossorganization collaboration projects, such as SourceForge, grid systems etc., have emerged. One of the fundamental requirements of these collaboration efforts is a storage system to store and exchange data. This storage system must be highly scalable and can efficiently aggregate the storage resources contributed by the participating organizations to deliver good performance for users. In this paper, we propose a storage system, Collaborative File Repository (CFR), 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 no...