Brian A. Coghlan

R-GMA: An Information Integration System for Grid Monitoring

Computational Grids are distributed systems that provide access to computational resources in a transparent fashion. Collecting and providing information about the status of the Grid itself is called Grid monitoring.

The Relational Grid Monitoring Architecture: Mediating Information about the Grid

We have developed and implemented the Relational Grid Monitoring Architecture (R-GMA) as part of the DataGrid project, to provide a flexible information and monitoring service for use by other middleware components and applications.R-GMA presents users with a virtual database and mediates queries posed at this database: users pose queries against a global schema and R-GMA takes responsibility for locating relevant sources and returning an answer. R-GMA’s architecture and mechanisms are general and can be used wherever there is a need for publishing and querying information in a distributed environment.We discuss the requirements, design and implementation of R-GMA as deployed on the DataGrid testbed. We also describe some of the ways in which R-GMA is being used.

Towards a grid-wide intrusion detection system

We describe SANTA-G (Grid-enabled System Area Networks Trace Analysis), an instrument monitoring framework that uses the R-GMA (Relational Grid Monitoring Architecture). We describe the CanonicalProducer, the component that allows for instrument monitoring, and how it would be used to construct the basis of a Grid-wide intrusion detection system.

First Prototype of the CrossGrid Testbed

The CrossGrid project is developing new grid middleware components, tools and applications with a special focus on parallel and interactive computing. In order to support the development effort and provide a test infrastructure, an international grid testbed has been deployed across 9 countries. Through the deployment of the testbed and its supporting services, CrossGrid is also contributing to another important project objective, the expansion of the grid coverage in Europe. This paper describes the status of the CrossGrid testbed.

A single-computer grid gateway using virtual machines

Grid middleware is enabling resource sharing between computing centres across the world and sites with existing clusters are eager to connect to the grid using middleware such as that developed by the LHC Computing Grid (LCG) project. However, the hardware requirements for access to the grid remain high: a standard LCG grid gateway requires four separate servers. We propose the use of virtual machine (VM) technology to run multiple OS instances, allowing a full grid gateway to be hosted on a single computer. This would significantly reduce the hardware, installation and management commitments required of a site that wants to connect to the grid. In this paper, we outline the architecture of a single-computer grid gateway. We evaluate implementations of this architecture using two popular open-source VMs: Xen and user-mode Linux (UML). Our results show that Xen outperforms UML for installation tasks and standard gateway operations. Configuration is similar to that of sites running multi-computer gateways, making it easy to keep site installation profiles synchronised. Our VM gateway architecture provides a low-cost entry path to the grid and will be of interest to many institutions wishing to connect their existing facilities.

The next generation Grid: an infrastructure for global business systems

This paper traces the evolution of the Grid and discusses the potential of the Grid as a future infrastructure adapted to the dynamics of global business systems – the global supply chain. Technology challenges facing global business systems are framed in volume (scale), real-time distribution, and real-time universal access to the visual state of the global business process and its associated physical and financial workflow. The future vision of the next generation grid as a an infrastructure for service oriented knowledge utilities makes the Grid a candidate infrastructure to address the challenge associated with the dynamics of global business systems – the global supply chain.

GridBuilder: A Tool for Creating Virtual Grid Testbeds

Grid software developers and Grid site administrators both require realistic testbeds where they can test applications and middleware before deployment on production infrastructure. Such testbeds should be dynamically reconfigurable to allow replication of real-world configurations. While the combination of service nodes needed for a particular application may vary greatly, there is a fixed set of node types which are used frequently: these are the building blocks needed to construct testbeds. We present GridBuilder: a web-based virtual machine (VM) manager that supports the rapid creation and customisation of Grid nodes based on standard configurations. GridBuilder allows users to create a library of filesystem images and then generate independent filesystems based on these images. Copy-on-write is used for fast initialisation and efficient use of disk space. GridBuilder uses standard Grid configuration tools to automatically configure the middleware on new Grid service nodes. Users can save and restore snapshots of nodes and can import images to create new node types.

Fault tolerance in the R-GMA information and monitoring system

R-GMA (Relational Grid Monitoring Architecture) [1] is a grid monitoring and information system that provides a global view of data distributed across a grid system. R-GMA creates the impression of a single centralised repository of information, but in reality the information can be stored at many different locations on the grid. The Registry and Schema are key components of R-GMA. The Registry matches queries for information to data sources that provide the appropriate information. The Schema defines the tables that can be queried. Without the combined availability of these components, R-GMA ceases to operate as a useful service. This paper presents an overview of R-GMA and describes the Registry replication design and implementation. A replication algorithm for the Schema has also been designed.

Deployment of grid gateways using virtual machines

Grid-Ireland, the national computational grid for Ireland, has a centrally managed core infrastructure: the installation and configuration of grid gateways at constituent sites are controlled from an Operations Centre based at Trinity College Dublin. We have developed tools to automate and simplify the deployment of Grid middleware to these sites. Virtual machine (VM) technology has performed an important role, allowing us to maximise the utilisation of server hardware and to simplify installation and management procedures. By running multiple OS instances, each on a VM, a full LCG-compatible Grid gateway can be hosted on a single computer. This has significantly reduced the hardware, installation and management investment needed to deploy a new site. In this paper, we summarise an evaluation of competing VM technologies and relate our experience with virtual machines to date. We also describe a single-computer Grid gateway based on the Xen VM system which we plan to deploy to eleven new sites in early 2005.

WEBCOM-G: A Candidate Middleware for Grid-Ireland

WebCom-G is a fledgling Grid Operating System, designed to provide independent service access through interoperability with existing middlewares. It offers an expressive programming model that automatically handles task synchronisation – load balancing, fault tolerance, and task allocation are handled at the WebCom-G system level – without burdening the application writer. These characteristics, together with the ability of its computing model to mix evaluation strategies to match the characteristics of the geographically dispersed facilities and the overall problem-solving environment, make WebCom-G a promising grid middleware candidate.