Network attached storage systems must provide highly available access to data while maintaining high performance, easy management, and maximum scalability. In this paper, we describe a clustered storage system that was designed with these goals in mind. The system provides a unified file system image across multiple nodes, which allows for simplified management of the system. Availability is preserved with multiple nodes and parity-striped data across these nodes. This architecture provides two

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... key contributions: the ability to use low-cost components to deliver scalable performance and the flexibility to specify redundancy and performance policy management on a file-by-file basis. The file system is also tightly integrated with standard distributed file system protocols thereby allowing it to be used in existing networks without modifying clients.