Overview Background: the user’s skills and knowledge Purpose: what the user wanted to do Work: what the user did Impression: what the user think of Ganga Suggestion: what the user wants from Ganga Ganga (GangaCamtology) User Experience Luke Heo Cambridge eScience Centre 26 February 2008

Background No Python experience - started to learn from October 2007 No Grid experience - started to learn from November 2007 Used gLiteUI 3.1.1(2) tarball and Ganga 4.4.4(5) Received intensive support from a Ganga developer (Karl Harrison)

Purpose Process image files on the Grid - gLite UI 3.1.2, Ganga RB: lcgwms01.grdpp.rl.ac.uk, lcgrb01.gridpp.rl.ac.uk - SE: serv02.hep.phy.cam.ac.uk Compare the job submission time - GLITE and EDG - Local and Internet image files Find an optimised solution for large-scale processing

Work Submitted 2225 jobs and processed 2million images via a Ganga script - some jobs failed due to proxy expiring, and to problems with CE, SE, and RB Found and resubmitted the failed jobs - via the Ganga job status and a script Measured job submission times - GLITE + Internet file, GLITE + local file, - EDG + Internet file, and EDG + local file

Good Impression Ganga as a grid browser/application for the Grid - enabled use of Grid resources without worrying about complicated Grid technologies CLI enables use of powerful Python scripts - easily submitted the required 2k jobs automatically - got statistic data (success and failed rate) via job status - resubmitted many failed jobs automatically Convenient to set the Grid environment via.gangarc - excluded an ever failing CE

Bad Impression Poor user guide - could not find a full Ganga user guide, though there are many quick user guides on the Internet Wanted some more simple commands - jobs(id).stdout: to read the output message of the job - jobs(id).stderror: to read the error message of the job Unable to renew proxy certificate automatically in a secure way - If the job submission time exceeds 24 hours, it fails due to the expiration of the proxy certificate on the worker node

Suggestions Continue to develop as a grid browser/application - Make easier to configure and use, more tolerant of Grid problems, and better at handling failures Write a full user guide - Provide enough information and explanation to run Ganga without a Ganga developer’s support Enable renewing a proxy certificate automatically - renew the proxy certificate before it expires