Cooperative caches offer huge amounts of caching memory that is not always used as well as it could be. We might find blocks in the cache that have not been requested for many hours. These blocks will hardly improve the performance of the system while the buffers they occupy could be better used to speed-up the I/O operations. In this paper, we present a family of simple prefetching algorithms that increase the file-system performance significantly. Furthermore, we also present a way to make any simple prefetching algorithm into an aggressive one that controls its aggressiveness not to flood the cache unnecessarily. All these algorithms and mechanisms have proven to increase the performance of two state-of-the-art parallel/distributed file systems: PAFS and xFS.