Efficient Cooperative Caching using Hints

We present a very low-overhead decentralized algorithm for cooperative caching that provides performance comparable to that of existing centralized algorithms. Unlike existing algorithms that rely on centralized control of cache functions, our algorithm uses hints (i.e. inexact information) to allow clients to perform these functions in a decentralized fashion. This paper shows that a hint-based system performs as well as a more tightly coordinated system while requiring less overhead. Simulations show that the block access times of our system are as good as those of the existing tightly-coordinated algorithms, while reducing manager load by more than a factor of 15, block lookup traffic by nearly a factor of two-thirds, and replacement traffic by more than a factor of 5. 1 Introduction Caching is a common technique for improving the performance of distributed file systems [Howard88, Nelson93, Sandberg85]. Client caches filter application I/O requests to avoid network and server traff..