Systeme für Hochleistungsrechnen. Seminar SS 2003

Systeme für Hochleistungsrechnen sind Parallelrechner, die eingesetzt werden, wenn die Rechenleistung herkömmlicher Einzelprozessorsysteme nicht ausreicht. Die früher verwendeten, eng gekoppelten Multiprozessorsysteme werden, dem Trend zur globalen Vernetzung folgend, zunehmend durch preiswertere, lose gekoppelte Rechnerverbünde aus Standardrechnerknoten und Massenspeichern ersetzt. Die lose Kopplung ergibt vielfältige neue Herausforderungen in der Koordinierung zwischen den Rechnerknoten wie auch innerhalb jedes Knotens, um die Ressourcen im Verbund effizient nutzen zu können. Dies betrifft die koordinierte Zuteilung von Prozessoren und Speicher auf Prozesse ebenso wie die selbstorganisierende Abstimmung der Kommunikation zwischen den Knoten unter Berücksichtigung der Verbundtopologie. Vielfältige aktuell diskutierte Lösungsansätze von der Hardwareschicht über das Betriebssystem bis zur Anwendungsschicht werden in einer Reihe von Beiträgen, die im Rahmen des Seminars "Systeme für Hochleistungsrechnen" im Sommersemester 2003 erarbeitet wurden, aufgezeigt und erörtert

Benchmarked Hard Disk Drive Performance Characterization and Optimization Based on Design of Experiments Techniques

This paper describes an experimental study offered by Designs of Experiments (DOE) within the defined factor domains to evaluate the factor effects of simultaneous characteristics on the benchmarked hard disk drive performance by proposing well-organized statistical models for optimizations. The numerical relations of the obtained models permit to predict the behaviors of benchmarked disk performances as functions of significant factors to optimize relevant criteria based on the needs. The experimental data sets were validated to be in satisfying agreement with predicted values by analyzing the response surface plots, contour plots, model equations, and optimization plots. The adequacy of the model equations were verified effectively by a prior generation disk drive within the same model family. The retained solutions for potential industrializations were the concluded response surface models of benchmarked disk performance optimizations. The comprehensive benchmarked performance modeling procedure for hard disk drives not only saves experimental costs on physical modeling but also leads to hard-to-find quality improvement solutions to manufacturing decisions

The Design of a High-Integrity Disk Management Subsystem

This dissertation describes and experimentally evaluates the design of the Logical Disk, a disk management subsystem that guarantees the integrity of data stored on disk even after system failures, while still providing performance competitive to other storage systems. Current storage systems that use the hard disk as storage medium, such as file systems, often do not provide sufficient protection against loss of data after a system failure. The designers of such systems are afraid that the amount of effort necessary for data protection would also result in too much loss of performance. The Logical Disk uses many different techniques to guarantee data integrity, including the support to execute multiple commands as one atomic action and avoiding `in-place updates' at all times. The techniques used to provide competitive performance include the technique of combining many, small write commands into one large, sequential, and thus efficient, write to disk, and clustering the data on disk continuously and automatically.Tanenbaum, A.S. [Promotor]Jonge, W. de [Copromotor

Freeblock Scheduling Outside of Disk Firmware

Freeblock scheduling replaces a disk drive's rotational latency delays with useful background media transfers, potentiallyallowing background disk I/O to occur with no impact on foreground service times. To do so, a freeblock scheduler must be able to very accurately predict the service time components of any given disk request | the necessary accuracy was not previously considered achievable outside of disk rmware. This paper describes the design and implementation of a working external freeblock scheduler running either as a user-level application atop Linux or inside the FreeBSD kernel. This freeblock scheduler can give 15% of a disk's potential bandwidth (over 3.1MB/s) to a background disk scanning task with almost no impact (less than 2%) on the foreground request response times. This increases disk bandwidth utilization by over 6