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Conference Paper

#### Duality Between Prefetching and Queued Writing with Parallel Disks

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##### Citation

Hutchinson, D. A., Sanders, P., & Vitter, J. S. (2001). Duality Between Prefetching
and Queued Writing with Parallel Disks. In F. Meyer auf der Heide (*Proceedings
of the 9th Annual European Symposium on Algorithms (ESA-01)* (pp. 62-73). Berlin, Germany: Springer.

Cite as: http://hdl.handle.net/11858/00-001M-0000-000F-3185-2

##### Abstract

Parallel 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 the integrated caching and
prefetching problem, in which 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
merge sort, addressing a question that has been open for some time.