An Improved Parallel Disk Scheduling Algorithm

We address the problems of prefetching and I/O scheduling for read-once reference strings in a parallel I/O system. Read-once reference strings, in which each block is accessed exactly once, arise naturally in applications like databases and video retrieval. Using the standard parallel disk model with D disks and a shared I/O buffer of size M , we present a novel algorithm, Red-Black Prefetching (RBP), for parallel I/O scheduling. The number of parallel I/Os performed by RBP is within O(D 1=3 ) of the minimum possible. Algorithm RBP is easy to implement and requires computation time linear in the length of the reference string. Through simulation experiments we validated the benefits of RBP over simple greedy prefetching. 1. Introduction Modern applications like multimedia servers, seismic databases, and visualization and graphics need access to large data sets that reside on external storage. The high data access rates demanded by such applications has resulted in the I/O subsyste..