AliEnFS - a Linux File System for the AliEn Grid Services

Among the services offered by the AliEn (ALICE Environment http://alien.cern.ch) Grid framework there is a virtual file catalogue to allow transparent access to distributed data-sets using various file transfer protocols. $alienfs$ (AliEn File System) integrates the AliEn file catalogue as a new file system type into the Linux kernel using LUFS, a hybrid user space file system framework (Open Source http://lufs.sourceforge.net). LUFS uses a special kernel interface level called VFS (Virtual File System Switch) to communicate via a generalised file system interface to the AliEn file system daemon. The AliEn framework is used for authentication, catalogue browsing, file registration and read/write transfer operations. A C++ API implements the generic file system operations. The goal of AliEnFS is to allow users easy interactive access to a worldwide distributed virtual file system using familiar shell commands (f.e. cp,ls,rm ...) The paper discusses general aspects of Grid File Systems, the AliEn implementation and present and future developments for the AliEn Grid File System.Comment: 9 pages, 12 figure

The AliEn system, status and perspectives

AliEn is a production environment that implements several components of the Grid paradigm needed to simulate, reconstruct and analyse HEP data in a distributed way. The system is built around Open Source components, uses the Web Services model and standard network protocols to implement the computing platform that is currently being used to produce and analyse Monte Carlo data at over 30 sites on four continents. The aim of this paper is to present the current AliEn architecture and outline its future developments in the light of emerging standards.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics (CHEP03), La Jolla, Ca, USA, March 2003, 10 pages, Word, 10 figures. PSN MOAT00

AliEn Resource Brokers

AliEn (ALICE Environment) is a lightweight GRID framework developed by the Alice Collaboration. When the experiment starts running, it will collect data at a rate of approximately 2 PB per year, producing O(109) files per year. All these files, including all simulated events generated during the preparation phase of the experiment, must be accounted and reliably tracked in the GRID environment. The backbone of AliEn is a distributed file catalogue, which associates universal logical file name to physical file names for each dataset and provides transparent access to datasets independently of physical location. The file replication and transport is carried out under the control of the File Transport Broker. In addition, the file catalogue maintains information about every job running in the system. The jobs are distributed by the Job Resource Broker that is implemented using a simplified pull (as opposed to traditional push) architecture. This paper describes the Job and File Transport Resource Brokers and shows that a similar architecture can be applied to solve both problems.Comment: 5 pages, 8 figures, CHEP 03 conferenc

Redefining the boundaries of interplanetary coronal mass ejections from observations at the ecliptic plane

On 2015 January 6-7, an interplanetary coronal mass ejection (ICME) was observed at L1. This event, which can be associated with a weak and slow coronal mass ejection, allows us to discuss on the differences between the boundaries of the magnetic cloud and the compositional boundaries. A fast stream from a solar coronal hole surrounding this ICME offers a unique opportunity to check the boundaries' process definition and to explain differences between them. Using Wind and ACE data, we perform a complementary analysis involving compositional, magnetic, and kinematic observations providing relevant information regarding the evolution of the ICME as travelling away from the Sun. We propose erosion, at least at the front boundary of the ICME, as the main reason for the difference between the boundaries, and compositional signatures as the most precise diagnostic tool for the boundaries of ICMEs.Comment: 9 pages and 7 figures in the original forma

A Carrington-like geomagnetic storm observed in the 21st century

In September 1859 the Colaba observatory measured the most extreme geomagnetic disturbance ever recorded at low latitudes related to solar activity: the Carrington storm. This paper describes a geomagnetic disturbance case with a profile extraordinarily similar to the disturbance of the Carrington event at Colaba: the event on 29 October 2003 at Tihany magnetic observatory in Hungary. The analysis of the H-field at different locations during the "Carrington-like" event leads to a re-interpretation of the 1859 event. The major conclusions of the paper are the following: (a) the global Dst or SYM-H, as indices based on averaging, missed the largest geomagnetic disturbance in the 29 October 2003 event and might have missed the 1859 disturbance, since the large spike in the horizontal component (H) of terrestrial magnetic field depends strongly on magnetic local time (MLT); (b) the main cause of the large drop in H recorded at Colaba during the Carrington storm was not the ring current but field-aligned currents (FACs), and (c) the very local signatures of the H-spike imply that a Carrington-like event can occur more often than expected.Comment: 18 pages, 2 figures, accepted for publication in SWS

Supergranular-scale magnetic flux emergence beneath an unstable filament

Here we report evidence of a large solar filament eruption on 2013, September 29. This smooth eruption, which passed without any previous flare, formed after a two-ribbon flare and a coronal mass ejection towards Earth. The coronal mass ejection generated a moderate geomagnetic storm on 2013, October 2 with very serious localized effects. The whole event passed unnoticed to flare-warning systems. We have conducted multi-wavelength analyses of the Solar Dynamics Observatory through Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager (HMI) data. The AIA data on 304, 193, 211, and 94 \AA sample the transition region and the corona, respectively, while HMI provides photospheric magnetograms, continuum, and linear polarization data, in addition to the fully inverted data provided by HMI. [...] We have observed a supergranular-sized emergence close to a large filament in the boundary of the active region NOAA11850. Filament dynamics and magnetogram results suggest that the magnetic flux emergence takes place in the photospheric level below the filament. Reconnection occurs underneath the filament between the dipped lines that support the filament and the supergranular emergence. The very smooth ascent is probably caused by this emergence and torus instability may play a fundamental role, which is helped by the emergence.Comment: 9 pages, 6 figures, online material at Journa

Estudio del Rhynchosauroides santanderiensis, n. sp., y otras nuevas huellas de pisadas en el Trias de Santander, con notas sobre el ambiente paleográfico

Procedentes del Trías del área de Puentenansa (Santander) se describen cuatro tipos de huellas de pisadas de reptiles de pequeño tamaño. Ninguno de los tipos se conocía anteriormente, pero sólo se ha dado nombre a uno de ellos (Rhynchosauroides santanderiensis, n.sp.).Se expone también, realizado a partir de datos petrológicos, un esbozo de las condiciones existentes en el área en la época en que vivieron los autores de las pistas. Este esbozo coincide con las conclusiones que pueden deducirse de la existencia y características de las huellas (zona marginal respecto al conjunto de la cuenca, sometida a inundaciones periódicas)