Search

In this paper we present the motivation, the design, and a recent demonstration of the UltraLight testbed at SC|05. The goal of the Ultralight testbed is to help meet the data-intensive computing challenges of the next generation of particle physics experiments with a comprehensive, network- focused approach. UltraLight adopts a new approach to networking: instead of treating it traditionally, as a static, unchanging and unmanaged set of inter-computer links, we are developing and using it as a dynamic, configurable, and closely monitored resource that is managed from end-to-end. To achieve its goal we are constructing a next-generation global system that is able to meet the data processing, distribution, access and analysis needs of the particle physics community. In this paper we will first present early results in the various working areas of the project. We then describe our experiences of the network architecture, kernel setup, application tuning and configuration used during the bandwidth challenge event at SC|05. During this Challenge, we achieved a record-breaking aggregate data rate in excess of 150 Gbps while moving physics datasets between many Grid computing sites.

Grid based systems require a database access mechanism that can provide seamless homogeneous access to the requested data through a virtual data access system, i.e. a system which can take care of tracking the data that is stored in geographically distributed heterogeneous databases. This system should provide an integrated view of the data that is stored in the different repositories by using a virtual data access mechanism, i.e. a mechanism which can hide the heterogeneity of the backend databases from the client applications. This paper focuses on accessing data stored in disparate relational databases through a web service interface, and exploits the features of a Data Warehouse and Data Marts. We present a middleware that enables applications to access data stored in geographically distributed relational databases without being aware of their physical locations and underlying schema. A web service interface is provided to enable applications to access this middleware in a language and platform independent way. A prototype implementation was created based on Clarens [4], Unity [7] and POOL [8]. This ability to access the data stored in the distributed relational databases transparently is likely to be a very powerful one for Grid users, especially the scientific community wishing to collate and analyze data distributed over the Grid., Comment: 8 pages, 6 figures, 1 table. Workshop on Web and Grid Services for Scientific Data Analysis at the Int Conf on Parallel Processing (ICPP05). Norway June 2005

Grid enabled physics analysis requires a workload management system (WMS) that takes care of finding suitable computing resources to execute data intensive jobs. A typical example is the WMS available in the LCG2 (also referred to as EGEE-0) software system, used by several scientific experiments. Like many other current grid systems, LCG2 provides a file level granularity for accessing and analysing data. However, application scientists such as high energy physicists often require a higher abstraction level for accessing data, i.e. they prefer to use datasets rather than files in their physics analysis. We have improved the current WMS (in particular the Matchmaker) to allow physicists to express their analysis job requirements in terms of datasets. This required modifications to the WMS and its interface to potential data catalogues. As a result, we propose a simple data location interface that is based on a Web service approach and allows for interoperability of the WMS with new dataset and file catalogues. We took a particular high energy physics experiment as the source for our study and show that physics analysis can be improved by our modifications to the current grid system.

The CMS experiment is currently developing a computing system capable of serving, processing and archiving the large number of events that will be generated when the CMS detector starts taking data. During 2004 CMS undertook a large scale data challenge to demonstrate the ability of the CMS computing system to cope with a sustained data- taking rate equivalent to 25% of startup rate. Its goals were: to run CMS event reconstruction at CERN for a sustained period at 25 Hz input rate; to distribute the data to several regional centers; and enable data access at those centers for analysis. Grid middleware was utilized to help complete all aspects of the challenge. To continue to provide scalable access from anywhere in the world to the data, CMS is developing a layer of software that uses Grid tools to gain access to data and resources, and that aims to provide physicists with a user friendly interface for submitting their analysis jobs. This paper describes the data challenge experience with Grid infrastructure and the current development of the CMS analysis system.

The requirement for information on portable, handheld devices demands the realization of increasingly complex applications for increasingly small and ubiquitous devices. This trend promotes the migration of technologies that were originally developed for desktop computers to handheld devices. With the onset of grid computing, users of handheld devices should be able to accomplish much more complex tasks, by accessing the processing and storage resources of the grid. This paper describes the development, features, and performance aspects of a grid enabled analysis environment designed for handheld devices. We also describe some differences in the technologies required to run these applications on desktop machines and handheld devices. In addition, we propose a prototype agent-based distributed architecture for carrying out high-speed analysis of physics data on handheld devices.

In order to prepare the Physic Technical Design Report, due by end of 2005, the CMS experiment needs to simulate, reconstruct and anlayse about 100 million events, corresponding to more than 200 TB of data. The data will be distributed to several Computing Centres. In order to provide access to the whole data sample to all the world-wide dispersed physicists, CMS is developing a layer of software that uses the grid tools provided by the LCG project to gain access to data and resources and that aims to provide physicists with a user friendly interface for submitting analysis jobs. The GRID tools used are both those already available in the LCG-2 release and those being developed in gain access to data and resources and that aims to provide physicists with a user friendly interface for submitting analysis jobs. The GRID tools used are both those already available in the LCG-2 release and those being developed in the framework of the ARDA project. This work describes the current status and the future developments of the CMS analysis system.