Z.W. Hendrikse

The distributed ASCI Supercomputer project

The Distributed ASCI Supercomputer (DAS) is a homogeneous wide-area distributed system consisting of four cluster computers at different locations. DAS has been used for research on communication software, parallel languages and programming systems, schedulers, parallel applications, and distributed applications. The paper gives a preview of the most interesting research results obtained so far in the DAS project.

VLAM-G: A Grid-based virtual laboratory

The Grid-based Virtual Laboratory AMsterdam (VLAM-G), provides a science portal for distributed analysis in applied scientific research. It offers scientists remote experiment control, data management facilities and access to distributed resources by providing cross-institutional integration of information and resources in a familiar environment. The main goal is to provide a unique integration of existing standards and software packages. This paper describes the design and prototype implementation of the VLAM-G platform. In this testbed we applied several recent technologies such as the Globus toolkit, enhanced federated database systems, and visualization and simulation techniques. Several domain specific case studies are described in some detail. Information management will be discussed separately in a forthcoming paper.

The implementation of dynamite: an environment for migrating PVM tasks

Parallel programming on clusters of workstations is increasingly attractive, but dynamic load balancing is needed to make efficient use of the available resources. Dynamite provides dynamic load balancing for PVM applications running under Linux and Solaris. It supports migration of individual tasks between nodes in a manner transparent both to the application programmer and to the user, implemented entirely in user space. Dynamically linked executables are supported, as are tasks with open files and with direct PVM connections. In this paper, we describe the technical aspects of migrating message-passing tasks.

VLAM-G: a grid-based virtual laboratory

The Grid-based Virtual Laboratory AMsterdam (VLAM-G) provides a science portal for distributed analysis in applied scientific research. By facilitating access to distributed compute and information resources held by multiple organizations, and providing remote experiment control, data management and information retrieval capabilities, it allows scientists to better analyze their data. The ability to use data from multiple sources and correlating these data sets without in-depth domain expertise is a prime goal of the system. This paper describes the design and an implementation prototype of the VLAMG platform. The feasibility of the system is demonstrated by a generalized sample scenario from the chemo-physical analysis domain.

Dynamic paths in multi-domain optical networks for grids

Many Grid applications require high bandwidth end-to-end connections between Grid resources in different domains. Fiber optic networks, owned by different providers, have to cooperate in a coordinated manner in order to provide an end-to-end connection. Currently, multi-domain optical network solutions require paper-based long-term contracts between administrative domains. This paper describes a solution for dynamically creating optical connections between different autonomous domains. This was implemented in the form of a Grid Service following the Open Grid Service Architecture. In our prototype, each switch belongs to a different network domain. Our Grid Service uses a toolkit based on the Generic Authorization, Authentication, and Accounting framework. This toolkit authorizes the use of optical infrastructure elements based on specific policies that are active within each domain. To complete our multi-domain authorization architecture, a Broker Service was also implemented. Our Broker Service interacts with the Grid Service instances to provide Grid application with a simplified way to set up end-to-end connections on demand.

Experiments with Migration of Message-Passing Tasks

The combined computing capacity of the workstations that are present in many organisations nowadays is often under-utilised, as the performance for parallel programs is unpredictable. Load balancing through dynamic task re-allocation can help to obtain a more reliable performance. The Esprit project Dynamite provides such an automated load balancing system. It can migrate tasks that are part of a parallel program using a message passing library. Currently Dynamite supports PVM only, but it is being extended to support MPI as well. The Dynamite package is completely transparent, i.e. neither system (kernel) nor application source code need to be modified. Dynamite supports migration of tasks using dynamically linked libraries, open files and both direct and indirect PVM communication. Monitors and a scheduler are included. In this paper, we first briefly describe the Dynamite system. Next we describe how migration decisions are made and report on some performance measurements.

Performance Measurements on Dynamite/DPVM

The total computing capacity of workstations can be harnessed more efficiently by using a dynamic task allocation system. The Esprit project Dynamite provides such an automated load balancing system, through the migration of tasks of a parallel program using PVM. The Dynamite package is completely transparent, i.e. neither system (kernel) nor application program modifications are needed. Dynamite supports migration of tasks using dynamically linked libraries, open files and both direct and indirect PVM communication. In this paper we briefly introduce the Dynamite system and subsequently report on a collection of performance measurements.

Evaluating the VLAM-G toolkit on the DAS-2

The Grid-based Virtual Laboratory AMsterdam (VLAM-G) provides a science portal for distributed analysis in applied scientific research. DAS-2 is a wide-area distributed computer of 200 Dual Pentium-III nodes, distributed over five Dutch universities. During the iGrid conference, the current reference implementation of VLAM-G was evaluated with an application from the chemo-physical application domain on the DAS-2. It was shown how data flows are instantiated on DAS-2 resources, driven by an information management system that is designed to extract information from raw data sets. Both the information management system and data processing modules are provided by the middleware of the Virtual Laboratory (VL). This paper describes the software and hardware setup of this study, and evaluates the use and performance of the VLAM-G science portal.

The VLAM-G Abstract Machine: A Data and Process Handling System on the Grid

This paper presents the architecture of the Virtual Laboratory Abstract-Machine (VL-AM), a data and process handling system on the Grid. This system has been developed within the context of the Virtual Laboratory (VL) project, which aims at building an environment for experimental science. The VL-AM solves problems commonly faces when addressing process and data handling in a heterogeneous environment. Although existing Grid technologies already provide suitable solutions most of the time, considerable knowledge and experience outside of the application domain is often required. The VL-AM makes these grid technologies readily available to a broad community of scientists. Moreover, it extends the current data Grid architecture by introducing an object-oriented database model handling complex queries on scientific information.