Draft grid storage namespace guidelines

The Grid can provide MICE not only with computing (number-crunching) power, but also with a secure global framework allowing users access to data. Although the focus is usually on the mass of experiment data, the Grid also opens up new possibilities for the storage and sharing of other material within the collaboration. This document provides an introduction to data storage on the Grid and describes the proposal for the directory structures to be used by MICE when registering data files stored on the Grid within a File Catalogue such as LFC

RFC: Data flow from the MICE experiment

This article can be accessed at the link below.This document sketches out the flow of data from the MICE experiment, as I currently understand it. This includes not only illustrating the structure of the data flow, but also setting out a consistent vocabulary with which to describe it. Many aspects of this data flow are either misunderstood by me, currently undecided, not yet implemented, or simply have never been considered before; so feedback is both welcomed and essential. Background information about job submission and file storage on the Grid can be found in previous MICE Notes and the references therein. In particular the first two sections of Note 247 are meant to provide a gentle introduction to Grid data storage from the MICE perspective, and timid MICE may wish to read those first

Notes from data flow workshop

Copyright @ 2009 MICEThis document summarises the discussions at the MICE Data Flow Workshop held at Brunel University on 30th June 2009. Background information about job submission and file storage on the Grid can be found in previous MICE Notes and the references therein. In particular the first two sections of Note 247 are meant to provide a gentle introduction to Grid data storage from the MICE perspective, and timid MICE may wish to read those first. The proposed data flow is described in MICE Note 252

Activation in the Vicinity of the MICE Target (SP7)

This document tabulates radiation levels measured in the vicinity of the MICE Target as given in the most recent Radiation Surveys available in the MICE document store

The online buffer

Copyright @ 2009 MICEThis is a discussion document regarding the proposed use of the Online Buffer. The Online Buffer is used to store locally the RAW data files created by the Event Builder, before they are uploaded to Castor by the data mover. The files may also be used by the online monitoring and reconstruction activities. At the Trigger-DAQ-Controls Review, the reviewers warned that this three-way activity might saturate the disks, and also that the file uploads to the Grid could conflict with the writing of DAQ data. It was proposed to ameliorate this by splitting the buffer into a set of independent volumes into which the DAQ data would be written on a round-robin basis; outgoing files would meanwhile be read only from one of the other volumes. Further, files being uploaded to the Grid would be staged on the transfer box’ system disk, as the (local) staging process is expected to be more deterministic and easier to control than transfers across the WAN

The reconstruction of digital holograms on a computational grid

Digital holography is greatly extending the range ofholography's applications and moving it from the lab into the field: a single CCD or other solid-state sensor can capture any number of holograms while numerical reconstruction within a computer eliminates the need for chemical development and readily allows further processing and visualisation of the holographic image. The steady increase in sensor pixel count leads to the possibilities of larger sample volumes, while smaller-area pixels enable the practical use of digital off-axis holography. However this increase in pixel count also drives a corresponding expansion of the computational effort needed to numerically reconstruct such holograms to an extent where the reconstruction process for a single depth slice takes significantly longer than the capture process for each single hologram. Grid computing - a recent innovation in large-scale distributed processing - provides a convenient means of harnessing significant computing resources in an ad-hoc fashion that might match the field deployment of a holographic instrument. We describe here the reconstruction of digital holograms on a trans-national computational Grid with over 10 000 nodes available at over 100 sites. A simplistic scheme of deployment was found to provide no computational advantage over a single powerful workstation. Based on these experiences we suggest an improved strategy for workflow and job execution for the replay ofdigital holograms on a Grid

Replay of digitally-recorded holograms using a computational grid

Since the calculations are independent, each plane within an in-line digital hologram of a particle field can be reconstructed by a separate computer. We investigate strategies to reproduce a complete sample volume as quickly and efficiently as possible using Grid computing. We used part of the EGEE Grid to reconstruct multiple sets of planes in parallel across a wide-area network, and collated the replayed images on a single Storage Element such that a subsequent particle tracking and analysis code might then be run. Although most of the sample volume is generated up to 20 times faster on a Grid, there are some stragglers which cause the reconstruction rate to slow, and a significant proportion of jobs get lost completely, leaving blocks missing from the sample volume. In the light of these experimental findings we propose some strategies for making Grid computing useful in the field of digital hologram reconstruction and analysis

Grid computing for the numerical reconstruction of digital holograms

Digital holography has the potential to greatly extend holography's applications and move it from the lab into the field: a single CCD or other solid-state sensor can capture any number of holograms while numerical reconstruction within a computer eliminates the need for chemical processing and readily allows further processing and visualisation of the holographic image. The steady increase in sensor pixel count and resolution leads to the possibilities of larger sample volumes and of higher spatial resolution sampling, enabling the practical use of digital off-axis holography. However this increase in pixel count also drives a corresponding expansion of the computational effort needed to numerically reconstruct such holograms to an extent where the reconstruction process for a single depth slice takes significantly longer than the capture process for each single hologram. Grid computing - a recent innovation in largescale distributed processing -provides a convenient means of harnessing significant computing resources in an ad-hoc fashion that might match the field deployment of a holographic instrument. In this paper we consider the computational needs of digital holography and discuss the deployment of numericals reconstruction software over an existing Grid testbed. The analysis of marine organisms is used as an exemplar for work flow and job execution of in-line digital holography

Beamline magnet polarity indication

Copyright @ 2010 MICEThe “Convention on MICE Beam Line Magnet Polarities” (MICE Note 198) defines the electrical input needed for the correct magnetic performance of each magnet, and identifies “positive” and “negative” terminals at the magnets and hence associates the labels “positive” and “negative” (and associated colouring) with the cables. This can result in "positive" cables having to be connected to the negative terminal on the power supply (and vice versa), which was not accepted by the electricians. It would seem preferable to have the cables labelled using a scheme that does NOT directly incorporate (or imply) the words “positive” and “negative”, or the associated colours of red and black. Beyond this, the aim here is neither to contradict nor supersede MICE Note 198. The aim is a scheme that makes it straightforward to open a cabinet in the MICE Hall and confirm that the wiring is correct with a simple visual check. This is achieved by i) labelling one set of leads at the magnet end with the word "reference"; and ii) labelling one set of leads at the supply end with the word "beamline". Then: At the MAGNETS: The “reference” leads are permanently connected to the “positive” terminal At the SUPPLIES: If the “beamline” leads are connected to the positive output, have a “positive beamline” If the “beamline” leads are connected to the negative output, have a “negative beamline”

Illumination system for the MICE tracker station assembly QA

Copyright @ 2007 MICEThis document describes the design and preparation of the optical system used to illuminate the scintillating-fibre planes to be used in the MICE Tracker. This illumination test during the tracker station assembly is a part of the quality assurance (QA) scheme. The optical design uses a two-stage approach: first, cylindrical optics are used to focus the round beam from the LED into to a long, thin shape. A mechanical slit is placed here to select an evenly illuminated region, providing it with well-defined edges. The second stage is a set of relay optics which project an image of the slit aperture on to the scintillating-fibre plane. A useful consequence of using relay optics rather than a simple slit close to the fibre plane is that wear or accidental damage to the fibres are avoided when the illumination system is being scanned across