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Este trabalho se inicia com uma discussão sobre as principais características dos Sistemas de Arquivos Distribuídos, ou seja, espaço de nomes, localização, cache, consistência, replicação, disponibilidade, escalabilidade, heterogeneidade, tolerância a falhas e segurança. Analisamos diversos sistemas de arquivos existentes quanto a estas características dando especial atenção aos sistemas NFS, Andrew, Coda, Sprite, Zebra, Harp, Frolic e Echo. Descrevemos alguns modelos analíticos para o comportamento de sistemas de arquivos distribuídos e, em seguida, apresentamos um novo modelo para sistemas baseados em leases - um mecanismo para a garantia de consistência em sistemas distribuídos. Finalmente, descrevemos a nossa implementação do sistema de arquivos distribuído SODA - que utiliza leases - apresentando dados sobre o seu desempenho. / We begin with a discussion of some of the main characteristics of Distributed File Systems, namely locality, name space, cache, consistency, replication, availability, scalability, heterogeneity, fault tolerance and security. We analyze several file systems based on these characteristics. We focus mainly on NFS, Andrew, Coda, Sprite, Zebra, Harp, Frolic, and Echo. We then describe some analytical models of the behavior of distributed file systems. After that we present a new model of systems based on leases - a mechanism to assure consistency on a distributed system. Finally we describe our implementation of the SODA distributed file system - which uses leases - presenting some results on its performance.

Presentation held on the 123. Unix-Stammtisch. It contains information about the usage of Linux on embedded systems. The boot process of Linux, the design of an embedded system environment and small libraries and tools are discussed in detail. / Vortrag zum 123. Unix Stammtisch der TU-Chemnitz. Befasst sich mit dem Entwurf und Betrieb von eingebetteten Systemen mit dem Betriebssystem Linux. Von der D-Box bis zur Linux-Armbanduhr, der Linux-Boot Prozess, Aufbau einer Linuxumgebung undminimalistisches Bibiotheken.

Bekanntlich gibt es für fast jede erdenkliche Aufgabe ein Open-Source-Programm. Bis auf einige Ausnahmen ist das Angebot an Software für Amateurastronomen allerdings recht unübersichtlich. Der Vortrag soll deshalb eine Übersicht über verschiedene Software-Projekte geben, die für Astrofotografie und astronomische Beobachtungen nützlich sind. Einfache Demonstrationen werden die Einsatzmöglichkeiten dieser Programme verdeutlichen und sollen dazu anregen, den Nachtimmel selbst mit Feldstecher und Kamera zu erkunden.

Este trabalho se inicia com uma discussão sobre as principais características dos Sistemas de Arquivos Distribuídos, ou seja, espaço de nomes, localização, cache, consistência, replicação, disponibilidade, escalabilidade, heterogeneidade, tolerância a falhas e segurança. Analisamos diversos sistemas de arquivos existentes quanto a estas características dando especial atenção aos sistemas NFS, Andrew, Coda, Sprite, Zebra, Harp, Frolic e Echo. Descrevemos alguns modelos analíticos para o comportamento de sistemas de arquivos distribuídos e, em seguida, apresentamos um novo modelo para sistemas baseados em leases - um mecanismo para a garantia de consistência em sistemas distribuídos. Finalmente, descrevemos a nossa implementação do sistema de arquivos distribuído SODA - que utiliza leases - apresentando dados sobre o seu desempenho. / We begin with a discussion of some of the main characteristics of Distributed File Systems, namely locality, name space, cache, consistency, replication, availability, scalability, heterogeneity, fault tolerance and security. We analyze several file systems based on these characteristics. We focus mainly on NFS, Andrew, Coda, Sprite, Zebra, Harp, Frolic, and Echo. We then describe some analytical models of the behavior of distributed file systems. After that we present a new model of systems based on leases - a mechanism to assure consistency on a distributed system. Finally we describe our implementation of the SODA distributed file system - which uses leases - presenting some results on its performance.

Presentation held on the 123. Unix-Stammtisch. It contains information about the usage of Linux on embedded systems. The boot process of Linux, the design of an embedded system environment and small libraries and tools are discussed in detail. / Vortrag zum 123. Unix Stammtisch der TU-Chemnitz. Befasst sich mit dem Entwurf und Betrieb von eingebetteten Systemen mit dem Betriebssystem Linux. Von der D-Box bis zur Linux-Armbanduhr, der Linux-Boot Prozess, Aufbau einer Linuxumgebung undminimalistisches Bibiotheken.

Bekanntlich gibt es für fast jede erdenkliche Aufgabe ein Open-Source-Programm. Bis auf einige Ausnahmen ist das Angebot an Software für Amateurastronomen allerdings recht unübersichtlich. Der Vortrag soll deshalb eine Übersicht über verschiedene Software-Projekte geben, die für Astrofotografie und astronomische Beobachtungen nützlich sind. Einfache Demonstrationen werden die Einsatzmöglichkeiten dieser Programme verdeutlichen und sollen dazu anregen, den Nachtimmel selbst mit Feldstecher und Kamera zu erkunden.

International Telemetering Conference Proceedings / November 04-07, 1991 / Riviera Hotel and Convention Center, Las Vegas, Nevada / In this paper we describe the design of the REAL/STAR 2000 system, a highperformance real-time computer for telemetry applications. The REAL/STAR 2000 is a symmetric, tightly-coupled multiprocessor, optimized for real-time processing. The system provides a high level of scalability and flexibility by supporting three configurations: single, dual, and quad processor configurations, based on Motorola 88100 RISC processors. The system runs the multiprocessor REAL/IX operating system, a real-time implementation of the AT&T UNIX System V. It compiles with BCS and OCS standards, meets the POSIX 1003.1 standard, and has the current functionality of the emerging POSIX 1003.4 real-time standard. The REAL/STAR 2000 promotes an open system approach to real-time computing by supporting major industry standards. Benchmark results are also presented in the paper.

International Telemetering Conference Proceedings / October 29-November 02, 1990 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The Loral Instrumentation System 500 configured as an Advanced Commanding and Telemetry System (ACTS) supports the acquisition of multiple telemetry downlink streams, and simultaneously supports multiple uplink command streams for today’s satellite vehicles. By using industry and federal standards, the system is able to support, without relying on a host computer, a true distributed dataflow architecture that is complemented by state-of-the-art RISC-based workstations and file servers.

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / This paper discusses the requirements and design of a multi-platform system software for control, status, calibration and testing of a telemetry system.