The Taub Faculty of Computer Science Events and Talks

In cooperative storage caching, clients may access blocks directly from each other’s caches. Previous studies treated all the cooperating caches as a single pool, maximizing overall system performance at the price of possibly degraded performance for individual clients. In light of the popularity of many P2P mechanisms, we re-evaluate the concept of cooperative caching, considering selfish clients that cooperate only if they benefit from the interaction. This is the first study that considers selfish clients in the context of cooperative storage caching. We present and analyze several novel cooperative caching approaches for varying degrees of client selfishness. Our evaluation focuses on the performance as well as the energy requirements of these approaches, on a wide range of systems and two workload domains. We show that choosing the best cooperative approach can decrease the system’s I/O delay by as much as 87%, while imposing cooperation when unwarranted might increase it by as much as 92%. We identify the situations that are especially vulnerable to such choices, as well as those which preclude cooperation altogether. Joint work with Assaf Schuster and Michael Factor (IBM Haifa)