Model-Based Monitoring in Large-Scale Distributed Systems

Monitoring remains an important problem in computer science. This thesis describes which monitor information is needed to analyze distributed service environments. This thesis also describes how to get these information and how to store them in a monitoring database. The resulting model is used to describe a distributed media content environment and a simulation system that runs on the CLIC helps to generate measurements as in real systems.Monitoring ist ein wichtiges Problem in der Informatik. In dieser Arbeit werden die benoetigten Daten beschrieben, welche zur Analyse von verteilten Dienstumgebungen dienen. Weiterhin wird beschrieben, wie man diese Daten messen und in einer geeigneten Datenbank speichern kann. Das daraus entstehende Modell wird verwendet um eine verteilte Medien-Daten-Umgebung zu beschreiben und eine Simulation auf dem CLIC erzeugt Messdaten wie sie in realen Systemen vorkommen

Long Term Resource Allocation in Video Delivery Systems

In typical video delivery systems offering programs on-demand, service should be be nearly immediate and continuous. A video server can provide this type of service by reserving sufficient network and server resources for the duration of playout. Scalability and reduced cost can be achieved using a single channel to serve multiple customers waiting for the same program (referred to as batching). Batching is especially useful during high load periods typically occuring during evening prime time hours. Typical channel allocation algorithms use a greedy, allocateas -needed policy. Variations in system load can cause these algorithms to suffer poor and unpredictable short-term performance, and non-optimal long term performance. In this paper, we develop a set of realistic workloads, identify the limitations of greedy allocation algorithms, and propose a set of rate-based allocation schemes to solve these limitations. The performance of various video delivery systems are simulated..