Red-black prefetching: An approximation algorithm for parallel disk scheduling

We address the problem of I/O scheduling of read-once reference strings in a multiple-disk parallel I/O system. We present a novel online algorithm, Red-Black Prefetching (RBP), for parallel I/O scheduling. In order to perform accurate prefetching; RBP uses L-block lookahead. The performance of RBP is analyzed in the standard parallel disk model with D independent disks and a shared I/O buffer of size M. We show that the number of parallel I/Os performed by RBP is within a factot Theta(max{root MD/L, D-1/3}) of the number of I/Os done by the optimal offline algorithm. This ratio is within a canstant factor of the best possible when L is L = O(MD1/3).