Robert Harakaly

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The deployment of large scale grids generates new challenges in system and network monitoring. Users and distributed applications need to access logical and up to date information on sites reachability, links performances and services availability. In this paper, we propose a presentation model suitable for grid environments, and we present the tool(More)
A Grid Network monitoring and performance measurement infrastructure is a key component of a large-scale Grid. Requirements for network monitoring with respect to Grid operations as well as performance characteristics and their relevance to Grid context have to be carefully identified before realizing such a system. In this paper we analyze the main issues(More)
A tool able to predict the behavior of the network in a Global computing environment could help the users to obtain better performance. In this paper we study the accuracy of the Network Weather Service (NWS) networking features and specifically the TCP throughput measurement and prediction. We studied the NWS forecast stability and confidence level on(More)
The complexity of Grid environments is growing as more projects and applications appear in this quick-evolving domain. Widespread applications are distributed over thousands of computing elements, various communities of users are aggregated into virtual organizations, resources availability is more and more dynamic and final locations of jobs cannot be(More)
The fast expansion of Grid technologies emphasizes the importance of network performance measurement. Some network measurement methods, like TCP throughput or latency evaluation, are very sensitive to concurrent measurements that may devalue the results. This paper presents the Probes Coordination Protocol (PCP) which can be used to schedule different(More)
In grids, many control subsystems are implemented by group of distributed agents that need to be coordinated and synchronised. In this paper we present a tool that implements a coordination protocol based on a generic, extensible and personalisable token passing protocol. We show how this tool performs different types of synchronisation tasks in a real Grid(More)
We have measured the ultralow temperature and low field magnetic susceptibility of the 4/7 phase of two-dimensional 3He adsorbed on graphite preplated by one layer of 4He. The experiments are performed by progressively adding 4He to the system, thus suppressing in a controlled way the 3He atoms trapped in substrate heterogeneities. This procedure enables us(More)
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