File caching is essential to good performance in a distributed system, especially as processor speeds and memory sizes continue to improve rapidly while disk latencies do not. Stateless-server systems, such as NFS, cannot properly manage client file caches. Stateful systems, such as Sprite, can use explicit cache consistency protocols to improve both cache consistency and overall performance. By modifying NFS to use the Sprite cache consistency protocols, we isolate the effects of the

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... y mechanism from the other features of Sprite. We find dramatic improvements on some, although not all, benchmarks, suggesting that an explicit cache consistency protocol is necessary for both correctness and good performance.