Brezany, Peter

Cortes, Toni

Nicole, Denis A.

Winslett, Marianne

English

Southampton (e-Prints Soton)

Topic 18Parallel I/O and Storage TechnologyPeter Brezany, Marianne Winslett, Denis A. Nicole, and Toni CortesTopic ChairpersonsIntroductionInput and output (I/O) is a major performance bottleneck for large-scale scien-tiﬁc applications running on parallel platforms. For example, it is not uncom-mon that performance of carefully tuned parallel programs can slow dramaticallywhen they read or write ﬁles. This is because many parallel applications need toaccess large amounts of data, and although great advances have been made inthe CPU and communication performance of parallel machines, similar advanceshave not been made in their I/O performance. The densities and capacities ofdisks have increased signiﬁcantly, but improvement in performance of individualdisks has not followed the same pace. For parallel computers to be truly us-able for solving real, large-scale problems, the I/O performance must be scalableand balanced with respect to the CPU and communication performance of thesystem. Parallel I/O techniques can help to solve this problem by creating mul-tiple data paths between memory and disks. However, simply adding disk drivesto an I/O systemwithout considering the overall software design will im proveperformance only marginally.The parallel I/O and storage research community is pursuing solutions inseveral diﬀerent areas in order to solve the problem. Active areas of researchinclude disk arrays, network-attached storage, parallel and distributed ﬁle sys-tems, theory and algorithms, compiler and language support for I/O, runtimelibraries, reliability and fault tolerance, large-scale scientiﬁc data management,database and multimedia I/O, real-time I/O, and tertiary storage. The MPI-IOinterface, deﬁned by the MPI Forumas part of the MPI-2 standard, aim s toprovide a standard, portable API that enables implementations to deliver highI/O performance to parallel applications.The Parallel I/O Archive at Dartmouth, http://www.cs.dartmouth.edu/pariois an excellent resource for further information on the subject. It has a compre-hensive bibliography and links to various I/O projects.Papers in this TrackThis year nine papers, fromthree continents and ﬁve countries, were subm itted.All papers were reviewed by three or more referees. Using the referees’ reportsguidelines, the program committee picked three papers for publication and pre-sentation at the conference. These were presented in one session.R. Sakellariou et al. (Eds.): Euro-Par 2001, LNCS 2150, pp. 887–888, 2001.c  Springer-Verlag Berlin Heidelberg 2001888 Peter Brezany et al.The ﬁrst paper, by Hakan Ferhatosmanoglu, Divyakant Agrawal and AmrEl Abbadi, explores optimal partitioning techniques for data stored in largespatial databases for diﬀerent types of queries, and develops multi-disk allocationtechniques that maximize the degree of I/O parallelism obtained during theretrieval. The authors show that hexagonal partitioning has optimal I/O cost forcircular queries compared to all possible non-overlapping partitioning techniquesthat use convex regions. The second paper, by Xavier Molero, Federico Silla,Vicente Santonja and Jos´ e Duato, proposes several strategies for dealing withshort control messages and analyzes their impact on the performance of storagearea networks. This analysis is carried out for a fully adaptive routing algorithmin the context of diﬀerent network topology environments. The third paper,by Jonathan Ilroy, Cyrille Randriamaro and Gil Utard, deals with improvingthe performance of the MPI-IO implementation running on top of the ParallelVirtual File System (PVFS). Their optimization mainly focuses on the collectiveI/O functionality of MPI-IO.

Topic 18 Parallel I/O and Storage Technology

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