Ben Segal

Models for replica synchronisation and consistency in a data grid

Data grids are currently proposed solutions to large-scale data management problems, including efficient file transfer and replication. Large amounts of data and the world-wide distribution of data stores contribute to the complexity of the data management challenge. Recent architecture proposals and prototypes deal with replication of read-only files but do not address the replica synchronisation problem. We propose a new data grid service, called the Grid Consistency Service (GCS), that sits on top of existing data grid services and allows for replica update synchronisation and consistency maintenance. We give models for different levels of consistency, provided to the Grid user and discuss how they can be included into a replica consistency service for a data grid.

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.

CernVM Co-Pilot: an Extensible Framework for Building Scalable Computing Infrastructures on the Cloud

CernVM Co-Pilot is a framework for instantiating an ad-hoc computing infrastructure on top of managed or unmanaged computing resources. Co-Pilot can either be used to create a stand-alone computing infrastructure, or to integrate new computing resources into existing infrastructures (such as Grid or batch). Unlike traditional middleware systems, Co-Pilot components communicate using the Extensible Messaging and Presence protocol (XMPP). This allows the system to be easily scaled in case of a high load, and it also simplifies the development of new components. In this contribution we present the latest developments and the current status of the framework, discuss how it can be extended to suit the needs of a particular community, as well as describe the operational experience of using the framework in the LHC@home 2.0 volunteer computing project.

Volunteer Clouds and Citizen Cyberscience for LHC Physics

Computing for the LHC, and for HEP more generally, is traditionally viewed as requiring specialized infrastructure and software environments, and therefore not compatible with the recent trend in volunteer computing, where volunteers supply free processing time on ordinary PCs and laptops via standard Internet connections. In this paper, we demonstrate that with the use of virtual machine technology, at least some standard LHC computing tasks can be tackled with volunteer computing resources. Specifically, by presenting volunteer computing resources to HEP scientists as a volunteer cloud, essentially identical to a Grid or dedicated cluster from a job submission perspective, LHC simulations can be processed effectively. This article outlines both the technical steps required for such a solution and the implications for LHC computing as well as for LHC public outreach and for participation by scientists from developing regions in LHC research.

LHC@Home: a BOINC-based volunteer computing infrastructure for physics studies at CERN

Abstract The LHC@Home BOINC project has provided computing capacity for numerical simulations to researchers at CERN since 2004, and has since 2011 been expanded with a wider range of applications. The traditional CERN accelerator physics simulation code SixTrack enjoys continuing volunteers support, and thanks to virtualisation a number of applications from the LHC experiment collaborations and particle theory groups have joined the consolidated LHC@Home BOINC project. This paper addresses the challenges related to traditional and virtualized applications in the BOINC environment, and how volunteer computing has been integrated into the overall computing strategy of the laboratory through the consolidated LHC@Home service. Thanks to the computing power provided by volunteers joining LHC@Home, numerous accelerator beam physics studies have been carried out, yielding an improved understanding of charged particle dynamics in the CERN Large Hadron Collider (LHC) and its future upgrades. The main results are highlighted in this paper.

CernVM WebAPI - Controlling Virtual Machines from the Web

Lately, there is a trend in scientific projects to look for computing resources in the volunteering community. In addition, to reduce the development effort required to port the scientific software stack to all the known platforms, the use of Virtual Machines (VMs)u is becoming increasingly popular. Unfortunately their use further complicates the software installation and operation, restricting the volunteer audience to sufficiently expert people. CernVM WebAPI is a software solution addressing this specific case in a way that opens wide new application opportunities. It offers a very simple API for setting-up, controlling and interfacing with a VM instance in the users computer, while in the same time offloading the user from all the burden of downloading, installing and configuring the hypervisor. WebAPI comes with a lightweight javascript library that guides the user through the application installation process. Malicious usage is prohibited by offering a per-domain PKI validation mechanism. In this contribution we will overview this new technology, discuss its security features and examine some test cases where it is already in use.

Why HEP Invented the Web

We are going to tell part of the story, little-known by most people, of how one of the most profound and revolutionary developments in information technology, the invention of the World Wide Web, occurred at CERN, the High Energy Physics laboratory in Geneva. In fact one man, Tim Berners-Lee, invented the Web, not “HEP”. So our question should really be re-phrased as: “What was the influence of HEP in leading to the Web’s invention?” In the discussion that follows, we will make use of some personal recollections, partly my own but also those of Sir Tim Berners-Lee himself (“TB-L” in what follows) in his book “Weaving the Web” [1] (abbreviated below as “WtW”).

Architecture and protocols of STELLA: A European experiment on satellite interconnection of local area networks

STELLA (Satellite Transmission Experiment Linking Laboratories) is a European wide-band data transmission experiment. STELLA makes use of the European Orbital Test Satellite (OTS) which provides a 2 Mb/s broadcast data transmission channel. The first phase of the STELLA project (STELLA/I) is summarized. The more important design characteristics of an improved version (STELLA/II) of STELLA/I are emphasized. Collaboration between STELLA/II and UNIVERSE projects in the framework of COST-11Bis is then outlined.