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Im SFB 342 "Methoden und Werkzeuge zur Nutzung paralleler Rechnerstrukturen" ist der Lehrstuhl fuer Rechnertechnik und Rechnerorganisation (LRR-TUM) fuer die Bereitstellung grundlegender Systemumgebungen und Werkzeuge durch das Teilprojekt A1 zustaendig. In diesen Rahmen ist die vorliegende Arbeit entstanden. Sie erklaert den Einsatz neuartiger und leistungsfaehiger Netztechnologien zur Parallelverarbeitung auf Netzen aus Arbeitsplatzrechnern und untersucht die Tragfaehigkeit dieser Vorgehensweise. Zentralen Gesichtspunkt hierbei bildet die eingehende Untersuchung erzielbarer Bandbreiten und Latenzzeiten. Die durchgefuehrten Messungen bilden schliesslich die Grundlage zur Ableitung von Richtlinien zur Optimierung der Kommunikation aus Systemsicht. Die Arbeit dient damit innerhalb des Querschnittsprojekts "Universell programmierbare Architektur und Basis-Software" (UPAS) sowohl als Entscheidungshilfe ueber den Einsatz ATM-vernetzter Systeme als auch zur Unterstuetzung bei der Verbesserung der Leistungsfaehigkeit von Anwendungen, die auf ATM-Clustern laufen.

In 1994, LRR-TUM obtained a research grant from the Intel Foundation for design and implementation of PFSLib, a parallel file system library which provides source code compatibility with Intel's parallel file system PFS. Its primary purpose is to work together with NXLib as an emulator of a Paragon supercomputer. Furthermore, PFSLib can be used as a stand-alone software product together with other parallel programming environments like e.g. PVM. Finally, PFSLib serves as a research platform to investigate issues of parallel file systems like e.g. file distribution or design of the user interface. This document will at first give an introduction into the issues connected with parallel file sytems. The second chapter will give an extended overview over the state of the art in the field of parallel I/O. The main aspect of this investigation will concentrate on the user interfaces of current parallel file systems. Chapter 3 describes in detail concepts of the PFSLib's design and implementation. A presentation of essential data structures and the flow of control and information throughout PFSLib calls will be given. Finally, chapter 4 puts the project of PFSLib in relation to current research in the group at LRR-TUM and shows issues for future research. This report also comprises the PFSLib manual giving details on each PFSLib call. PFSLib may be distributed freely under the GNU license agreements and can be obtained at ftp://ftp.leo.orgbode.informatik.tu-muenchen.de/PFSlib/.

In this paper, we dicuss the the design and implementation of the PFSLib library wich offers the functionality of Intel's parallel file system PFS. It is intended to be used with parallel programming environments like PVM, P4, and NXLib on workstation clusters. We also present preliminary performance results of PFSLib in comparison to NFS.

Much computational power on state-of-the-art multicomputers like the Paragon is wasted with porting applications. Using networks of workstations is an attempt to withdraw this workload from multicomputer systems. Therefore an environment is needed which provides the programming interface of multicomputers on coupled workstations. The paper describes the design and implementation of the NXLib environment which allows to use Ethernet coupled workstations as a development platform for applications targeted for Intel Paragon systems.

Workstations provide an attractive platform to develop software. This paper describes the NXLib environment which enables users to use this platform to develop parallel applications. The source code compatibility of NXLib applications with Intel's Paragon multicomputer system easily allows to migrate these applications to a supercomputer. The performance which can be achieved with either platform is compared using two applications. In addition performance results of NXLib communication calls and comparisons with other widespread messagepassing libraries for workstation clusters are presented.

Networks of workstations are gaining growing importance in high performance computing. Programming environments like MMK/X [Ste93] or PVM [BDG+91] allow for exploiting the aggregate computational power of coupled workstations. A different approach is to use such local area networks as a development platform for parallel applications which should finally run on multicomputer systems. Therefore an environment on the workstations is required which offers the same programming model as the multicomputer system. The work which is presented here describes the NXLib environment which emulates a Paragon system on a network of workstations.