Hutchinson, David A.Sanders, PeterVitter, Jeffrey Scott2011-03-162011-03-162005D. A. Hutchinson, P. Sanders, and J. S. Vitter. “Duality Between Prefetching and QueuedWriting with Parallel Disks,” SIAM Journal on Computing, 34(6), 1443–1463, June 2005. An extended abstract appears in Proceedings of the 9th Annual European Symposium on Algorithms (ESA ’01), °Arhus, Denmark, August 2001, published in Lecture Notes in Computer Science, 2161, Springer, Berlin, Germany, 62–73. http://dx.doi.org/10.1137/S0097539703431573https://hdl.handle.net/1808/7176AMS subject classifications. 68W10, 68W20, 68W40, 68M20, 68P10, 68P20, 68Q17 DOI. 10.1137/S0097539703431573Parallel disks promise to be a cost effective means for achieving high bandwidth in applications involving massive data sets, but algorithms for parallel disks can be difficult to devise. To combat this problem, we define a useful and natural duality between writing to parallel disks and the seemingly more difficult problem of prefetching. We first explore this duality for applications involving read-once accesses using parallel disks. We get a simple linear time algorithm for computing optimal prefetch schedules and analyze the efficiency of the resulting schedules for randomly placed data and for arbitrary interleaved accesses to striped sequences. Duality also provides an optimal schedule for prefetching plus caching, where blocks can be accessed multiple times. Another application of this duality gives us the first parallel disk sorting algorithms that are provably optimal up to lower-order terms. One of these algorithms is a simple and practical variant of multiway mergesort, addressing a question that had been open for some time.en-USCachingExternal memoryLoad balancingLower boundPrefetchingRandomized algorithmArticle10.1137/S0097539703431573openAccess