Erwin Laure

Middleware for the Next Generation Grid Infrastructure

The aim of the EGEE (Enabling Grids for E-Science in Europe) project is to create a reliable and dependable European Grid infrastructure for e-Science. The objective of the EGEE Middleware Re-engineering and Integration Research Activity is to provide robust middleware components, deployable on several platforms and operating systems, corresponding to the core Grid services for resource access, data management, information collection, authentication & authorization, resource matchmaking and brokering, and monitoring and accounting. For achieving this objective, we developed an architecture and design of the next generation Grid middleware leveraging experiences and existing components essentially from AliEn, EDG, and VDT. The architecture follows the service breakdown developed by the LCG ARDA group. Our strategy is to do as little original development as possible but rather re-engineer and harden existing Grid services. The evolution of these middleware components towards a Service Oriented Architecture (SOA) adopting existing standards (and following emerging ones) as much as possible is another major goal of our activity.

File-based replica management

Data replication is one of the best known strategies to achieve high levels of availability and fault tolerance, as well as minimal access times for large, distributed user communities using a world-wide Data Grid. In certain scientific application domains, the data volume can reach the order of several petabytes; in these domains, data replication and access optimization play an important role in the manageability and usability of the Grid. In this paper, we present the design and implementation of a replica management Grid middleware that was developed within the EDG project [European DataGrid Project (EDG), http://www.eu-egee.org] and is designed to be extensible so that user communities can adjust its detailed behavior according to their QoS requirements.

Replica Management in the European DataGrid Project

Within the European DataGrid project, Work Package 2 has designed and implemented a set of integrated replica management services for use by data intensive scientific applications. These services, based on the web services model, enable movement and replication of data at high speed from one geographical site to another, management of distributed replicated data, optimization of access to data, and the provision of a metadata management tool. In this paper we describe the architecture and implementation of these services and evaluate their performance under demanding Grid conditions.

Advanced Replica Management with Reptor

Data replication is one of the best known strategies to achieve high levels of availability and fault tolerance, as well as minimal access times for large, distributed user communities using a world-wide Data Grid. In certain scientific application domains the data volume can reach the order of several petabytes; in these domains data replication and access optimization play an important role in the manageability and usability of the Grid.

Kinetic simulations of plasmoid chain dynamics

The dynamics of a plasmoid chain is studied with three dimensional Particle-in-Cell simulations. The evolution of the system with and without a uniform guide field, whose strength is 1/3 the asymptotic magnetic field, is investigated. The plasmoid chain forms by spontaneous magnetic reconnection: the tearing instability rapidly disrupts the initial current sheet generating several small-scale plasmoids that rapidly grow in size coalescing and kinking. The plasmoid kink is mainly driven by the coalescence process. It is found that the presence of guide field strongly influences the evolution of the plasmoid chain. Without a guide field, a main reconnection site dominates and smaller reconnection regions are included in larger ones, leading to an hierarchical structure of the plasmoid-dominated current sheet. On the contrary in presence of a guide field, plasmoids have approximately the same size and the hierarchical structure does not emerge, a strong core magnetic field develops in the center of the plasmoid in the direction of the existing guide field, and bump-on-tail instability, leading to the formation of electron holes, is detected in proximity of the plasmoids.

Performance engineering in data Grids

The vision of Grid computing is to facilitate worldwide resource sharing among distributed collaborations. With the help of numerous national and international Grid projects, this vision is becoming reality and Grid systems are attracting an ever increasing user base. However, Grids are still quite complex software systems whose efficient use is a difficult and error‐prone task. In this paper we present performance engineering techniques that aim to facilitate an efficient use of Grid systems, in particular systems that deal with the management of large‐scale data sets in the tera‐ and petabyte range (also referred to as data Grids). These techniques are applicable at different layers of a Grid architecture and we discuss the tools required at each of these layers to implement them. Having discussed important performance engineering techniques, we investigate how major Grid projects deal with performance issues particularly related to data Grids and how they implement the techniques presented. Copyright

Towards transparent integration of heterogeneous cloud storage platforms

The recent increase in popularity of Storage-as-a-Service cloud solutions influences the way scientists are managing their data. More and more academic groups store and work on their data outside the university domain. Hence, data aggregation and metadata management is becoming increasingly important. While most cloud storage systems offer convenient access APIs, they are rarely fully compatible with each other. This makes migration between backends, or integration of data located in various places, more complicated. A common answer to this vendor lock-in problem lies in adopting common standards. Although there are no commonly adopted standards for cloud storage, yet, the potentially most promising direction at the moment is SNIAs Cloud Data Management Interface (CDMI), which defines the semantics of handling data objects and the required metadata. In this paper we present our prototype implementation of CDMI-compatible proxy, which offers a transparent integration layer on top of both cloud systems and local storage infrastructures. The work is being conducted as part of the FP7 project VENUS-C and released under an open-source license.

OpusJava: A Java Framework for Distributed High Performance Computing

The past few years have dramatically changed the view of high performance applications and computing. While traditionally such applications have been targeted towards dedicated parallel machines, w ...

The Formation of a Magnetosphere with Implicit Particle-in-Cell Simulations

We demonstrate the improvements to an implicit Particle-in-Cell code, iPic3D, on the example of dipolar magnetic field immersed in the flow of the plasma and show the formation of a magnetosphere. ...

OpenACC acceleration of the Nek5000 spectral element code

We present a case study of porting NekBone, a skeleton version of the Nek5000 code, to a parallel GPU-accelerated system. Nek5000 is a computational fluid dynamics code based on the spectral element method used for the simulation of incompressible flow. The original NekBone Fortran source code has been used as the base and enhanced by OpenACC directives. The profiling of NekBone provided an assessment of the suitability of the code for GPU systems, and indicated possible kernel optimizations. To port NekBone to GPU systems required little effort and a small number of additional lines of code (approximately one OpenACC directive per 1000 lines of code). The naïve implementation using OpenACC leads to little performance improvement: on a single node, from 16 Gflops obtained with the version without OpenACC, we reached 20 Gflops with the naïve OpenACC implementation. An optimized NekBone version leads to a 43 Gflop performance on a single node. In addition, we ported and optimized NekBone to parallel GPU systems, reaching a parallel efficiency of 79.9% on 1024 GPUs of the Titan XK7 supercomputer at the Oak Ridge National Laboratory.