The Design and Evaluation of a Distributed Reliable File System

Peer-to-peer (P2P) systems are, in contrast to client-server (C/S) systems, fault-tolerant, robust, and scalable. While C/S distributed file systems, such as NFS (network file system) or SMB (server message block), do not scale with respect to the number of clients and exhibit a single point of failure, P2P file systems have the potential to cope with an increasing number of participants. Thus, this paper presents DRFS (distributed reliable file system), a P2P file system for cooperative environments. DRFS uses random, content-independent identifiers for data storage, while maintaining high performance and low overhead with many concurrent reads and writes. A dynamic replication mechanism ensures data availability, even under high churn. The application scenario considers an office environment, where DRFS is installed on employees´ machines, who store and request files. DRFS has been implemented using the Filesystem in Userspace (FUSE) interface, in order to provide users with transparent read and write operations. Experiments show the benefits of such a peer-to-peer architecture, when a small number of peers reads or writes in parallel: DRFS performs better than NFS, as soon as 6 peers read or write in parallel a 32 MB file. For unpopular files, it is also more reliable than IgorFS.