Buffer management for a D-disk parallel I/O system is considered in the context of randomized placement of data on the
disks. A simple prefetching and caching algorithm PHASE-LRU using bounded lookahead is described and analyzed. It is
shown that PHASE-LRU performs an expected number of I/Os that is within a factor  (logD/log logD) of the number
performed by an optimal off-line algorithm. In contrast, any deterministic buffe