Ba. Bar Grid Tim Adye Particle Physics Department Rutherford Appleton Laboratory PP Grid Team Coseners House 8 th November 2002 Tim Adye 1
Talk Plan • • • Ba. Bar distributed computing model RAL Tier A Remote job submission Ba. Bar VO and Authorisation Metadata Data distribution 8 th November 2002 Tim Adye 2
The Ba. Bar Collaboration 9 Countries 8 th November 2002 74 Institutions Tim Adye 566 Physicists 3
PEP-II e+e- Ring and Ba. Bar Detector LER (e+, 3. 1 Ge. V), I(e+ )=2. 1 A Linear Accelerator HER (e-, 9. 0 Ge. V), I(e- )=1. 0 A Ba. Bar PEP-II ring: C=2. 2 km BABAR May 26, 1999: 1 st events recorded by Ba. Bar
Ba. Bar’s Distributed Computing Model • Goal is to spread computing load much more around the collaboration • Simulation production is already distributed – 75% in the UK! • Now have three new “Tier A” centres • Lyon – Objectivity (database) analysis (since last year) • RAL – Kanga (ROOT micro. DST) analysis (from May 2002) • Padova – Reprocessing (just starting) • Also several “Tier C” sites (ie. Universities, 9 in UK) • Analysis data format (Kanga vs Objectivity) is a matter of heated debate at the moment • Whatever the future of Objectivity, Kanga (championed in UK/Germany) looks set to continue 8 th November 2002 Tim Adye 5
RAL Tier A • UK Mo. U with Ba. Bar reduces our common fund contributions in exchange for providing Tier A facility • RAL has now relieved SLAC of all Kanga analysis • Impressive takeup from UK and non-UK users • See Andrew’s talk • It is the primary repository of Kanga data • ~20 TB on disk • Ba. Bar analysis environment tries to mimic SLAC so external users feel at home • Grid job submission should greatly reduce this requirement 8 th November 2002 Tim Adye 6
Remote Job Submission Short term (this month!) • Allow SLAC or University users to submit Ba. Bar analysis jobs to RAL or Lyon Tier A sites from their home machines • dg-job-submit • Simplifies local development and debugging, while providing access to full dataset and large CPU farms • RAL vs IN 2 P 3 selected explicitly by user • “canned” JDL Requirements; dataset selection left to user • Why couldn’t we do this a year ago? • Ba. Bar authorisation (see later) • Gatekeeper needed to be able to submit to production farm • Define which Ba. Bar configuration files to send with job • Developed a procedure to merge all tcl files into one • Resource Broker reliability – better with EDG 1. 2. 8 th November 2002 Tim Adye 7
Remote Job Submission Medium term (early next year) • Allow remote submission to UK Farms and SLAC • In principle this is already set up • Select site (CE) based on user requirements • Eg. Dataset available, software release, etc. • Split job between sites based on available datasets • Already have demonstrator for a canned analysis job • http: //www. hep. man. ac. uk/groups/slacb/gridtest. html 8 th November 2002 Tim Adye 8
Ba. Bar VO and Authorisation • Use certificates from EDG and ESnet CAs for authentication • Authorisation required to identify Ba. Bar users • Provides access to Ba. Bar-specific facilities and environment • Cannot maintain grid-mapfile by hand • Doesn’t scale to 1202+ users • Use existing SLAC Ba. Bar user registration • • User provides certificate id at SLAC Automatic procedure checks AFS group and fills VO CEs use VO for authorisation Naturally handles people leaving the experiment 8 th November 2002 Tim Adye 9
Analysis Metadata • Currently have about a million Kanga files in a deep directory tree • Need a catalogue to facilitate data distribution and allow analysis datasets to be defined. • SQL database • Locates ROOT files associated with each dataset • Selections based on decay channel, run range, beam energy, reconstruction processing version, etc. • Each site has its own (My. SQL or Oracle) database • Includes a copy of SLAC database with local information (eg. files on local disk, files to import, local tape backups) • Some use of SRB for local Objectivity metadata at SLAC and Lyon 8 th November 2002 Tim Adye 10
Data Distribution • Kanga and Objectivity distribution currently handled by homegrown procedures • Use bbftp. bbcp soon. Will look at Grid. FTP • Next step is to run transfers using Grid job submission • Web control pages under development • Authorisation done using Grid certificates • Looking at SRB and RLS for data distribution 8 th November 2002 Tim Adye 11
Summary • Ba. Bar already has a highly distributed analysis environment • RAL Tier A saves Ba. Bar! • Want to use Grid job submission tools – now • Looking at SRB and RLS 8 th November 2002 Tim Adye 12
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