MAST / Fusion Grid Access

@ UKAEA

MAST / Fusion Grid access

MINUTES

1 September 2003

Background

David Muir has just completed an interface to the JET PPF system, which enables Transp runs executing on the fusion grid processors at pppl to access JET data via MDSplus. Since MAST will require a similar system in order to use the grid version of Transp, it would clearly be to their advantage to employ David Muir to create it.

The meeting considered the likely timescale & deliverables for this project.

The Fusion Grid

Figure 1 shows an overview of the Fusion Grid system, for the scenario where the end user is remote from both the data & compute server sites. Items of concern for the current project are

2 Run preparation - creating an Mdsplus tree which acts as an interface between Transp & tokamak data accessed by the Mdsplus data server

3 Job submission to the Grid system, using the Globus security package

6Retrieval of job output from pppl

Figure 2 shows details of the job preparation and submission system as currently implemented at JET. The critical component is the procedure TrWeb, which creates an Mdsplus tree TrData, using site specific code to access the stored tokamak data. The remaining elements ( Tr_start, Tr_send .. ) are already implemented for JET, and so can be used, at least initially, for system development.

Minutes

MDSplus server status ( JW )

All components for running a server exist, although a server is not actually running at present. Some development is / may be required for IDA 3 . Transp trees may be written directly to the server disk area, so only remote read access is necessary for the current project. However, if a server is running, this is likely to provoke demand for other facilities..

Data preparation ( RA )

Current software to prepare ( ASCII ) Ufiles for Transp input performs some significant data preparation - smoothing, de-Glitching, parameter estimation. Could run this automatically, create a Transp (sub?)tree for each shot - though some data would potentially be duplicated . Alternative is to perform data massage on demand, when MDSplus requests the data.

JET system performs routine manipulations ( change of units etc ) when data is requested. For non-standard manipulation, users generate their own copies of the signals ( private PPFs ).

Run Database

Needed to associate shots, runs, tree numbers , run descriptions etc. The JET database has ( not quite ) been converted from Access to php. It can be made available to MAST as soon as it has been completed.

Process distribution ( JEC )

The left hand column ( fig 2, TrWeb, trdata tree ) has to run at MAST.

The right hand column ( Tr_send ) transmits a 5 line ASCII file to the Grid server at pppl. This could conveniently be run at JET, to avoid maintaining two versions of Globus ( with associated firewall issues ) on site.

The centre column ( Tr_start .. ) is available on the JET analysis cluster, as part of the standard Transp distribution. A standalone distribution is also available, & this could be installed on MAST - slight possibility of problems with compilers, shared libraries ?

Output recovery

Has not been addressed ( no output available to recover, before the job submission & execution problems were solved ). Are the associated diagnostic output files available ( CB ) ?? Need to ask pppl about this .

Admin

JW would be line manager for the project, & raise contract
CB will negotiate for office space & desktop PC

Project specification

( Final details decided after main meeting )

Deliverables -

Components for interface to fusion grid, to include

Tree editor ( TrWeb ) configured for MAST data

Documentation

Job submission software on fuslwg, or
interface to Tr_start on JAC

Output retrieval procedure

Estimated timescale

Note that these estimates are somewhat imprecise, since the MDSplus server status is unknown, as is the number of different access codes . This will be clarified once the present system has been evaluated.

Should the above timings be an overestimate, there is plenty of additional development required to integrate trweb with the script based job submission interface, and to tailor the menu of input files displayed to be only those referenced in the namelist.