1. 16 th LHCb Software Week1 April 2004

2. 16 th LHCb Software Week1 April 2004 Happy April Fools Unfortunately, not yet … … but I hope so one day.

3. 16 th LHCb Software Week1 April 2004 Ian Stokes-Rees Introducing LCG to LHCb

4. 16 th LHCb Software Week1 April 2004 Summary Quick LCG Summary Getting started Accessing the LCG Job Submission on LCG Data Management on LCG References

5. 16 th LHCb Software Week1 April 2004 LCG: The Good News 10,000+ CPUs all at your disposal, and constantly growing Spread over Europe, North America and the rest of the world Largest general purpose grid computing cluster in the world

6. 16 th LHCb Software Week1 April 2004 LCG: Key Features Single sign-on via x509 PKI digital certificates Uniform file access across all LCG sites Ability to define multiple logical names for a single global file Replication and auto-replication facilities Automated scheduling of jobs to suitable resources Based on job requirements Based on resource availability/cluster loads Based on input and output data location Numerous API libraries to integrate LCG services into software

7. 16 th LHCb Software Week1 April 2004 LCG: The Reality Hard to get started x509 Digital Certificate takes time to acquire Commands not obvious System not always running 100%

8. 16 th LHCb Software Week1 April 2004 LCG: LHCb-Help ESUS: Experiment Specific User Support Ian Stokes-Rees Joel Closier ESUS rep 3??? savannah.cern.ch/ projects/lhcb-help Documentation Support System Links

9. 16 th LHCb Software Week1 April 2004 Summary of LCG Registration http://savannah.cern.ch/projects/lhcb-help Register on savannah.cern.ch Register for LHCb-Help Find your CA (Certificate Authority) Apply for x509 cert Meet your local RA (Registration Auth.) Receive CA signed cert Create browser and command-line versions of x509 cert 8.Save cert onto USB key (both browser and CLI versions), and make scp’able 9.Load cert into browser(s) 10.Register your certificate with the LHCb VO (Virtual Organisation) 11.Find a machine with the LCG User Interface Software installed All this is documented on the LHCb-Help Savannah site

10. 16 th LHCb Software Week1 April 2004 Getting Started: Digital Certificates You must apply for an x509 digital certificate Find your “local” CA e.g.: CERN: service-grid-ca.web.cern.ch UK e-Science: ca.grid-support.ac.uk CNRS: igc.services.cnrs.fr/Datagrid-fr It may take several days to receive your digital certificate, so please apply before you need it! Walk-through on LHCb-Help website Submit support request if you have problems

11. 16 th LHCb Software Week1 April 2004 LCG Demonstration

12. 16 th LHCb Software Week1 April 2004 Part 1: Review of Registration Savannah LHCb-Help CA Site CERN UK e-Science CNRS LCG/VO Registration Certificate: Data: Version: 3 (0x2) Serial Number: 1741 (0x6cd) Signature Algorithm: md5WithRSAEncryption Issuer: C=UK, O=eScience, OU=Authority, CN=CA/Email=ca-operator@grid- support.ac.uk Validity Not Before: Mar 5 17:41:30 2004 GMT Not After : Mar 5 17:41:30 2005 GMT Subject: C=UK, O=eScience, OU=Oxford, L=OeSC, CN=Ian Stokes- rees Subject Public Key Info: Public Key Algorithm: rsaEncryption RSA Public Key: (1024 bit)

13. 16 th LHCb Software Week1 April 2004 GK Close SE WN LCG Site Grid Topology SE UI RB Resource Broker Storage Element User Interface Gate Keeper Storage Element Worker Node

14. 16 th LHCb Software Week1 April 2004 Part 2: Job Description Language Executable = "/bin/hostname"; Arguments = "-f"; StdOutput = "std.out"; StdError = "std.err"; OutputSandbox = {"std.out","std.err"}; Other key JDL attributes: InputSandbox, InputData, StdInput, OutputData Environment Requirements, Rank See LCG-2 User Guide for more details

15. 16 th LHCb Software Week1 April 2004 Part 2: Submitting LCG Jobs grid-proxy-init grid-proxy-info edg-job-list-match hostname.jdl edg-job-submit hostname.jdl edg-get-status edg-job-get-logging-info edg-job-get-output

16. 16 th LHCb Software Week1 April 2004 Part 2: Useful Additions Options: --vo lhcb : usually required -i : list of job IDs -o : output of command -r : send job to specific resource.BrokerInfo file in Worker Node “home” directory with details of LCG site edg-brokerinfo to extract information from.BrokerInfo file Usual use case is to prepare a script which gets uploaded in InputSandbox and then executed

17. 16 th LHCb Software Week1 April 2004 Part 3: Data Management Types of LCG Files: file:// : local file lfn: : logical file name (LFN) guid: : global unique file ID (GUID) sfn:// : storage URL (SURL) :// : transfer URL (TURL)

18. 16 th LHCb Software Week1 April 2004 Part 3: Data Commands Copying file to Grid Storage: edg-rm cr -l lfn: Copies local file to grid storage and registers specified Logical File Name (LFN) Returns the guid: Copying file from Grid Storage: edg-rm cp file:// Finds file based on LFN and copies to specified path

19. 16 th LHCb Software Week1 April 2004 Part 3: Data Commands Replicating Files: edg-rm rep -d Puts replica of file at specified site Deleting Files: edg-rm del -s Deletes specified file from the specified site If SURL specified, -s option not required --all-available will remove all replicas

20. 16 th LHCb Software Week1 April 2004 Part 3: Data Commands Linking – Adding an LFN: edg-rm aa Adds LFN for specified GUID Accessing files from inside a job: Use edg-rm cp file:// to access Specify InputData in JDL, containing LFN or GUID See edg-gridftp-* commands for direct control of files on SE See LCG User Guide for more information

21. 16 th LHCb Software Week1 April 2004 LCG: What To Expect Job Execution: Currently looking at 6 minute overhead to process job completely Data Operations: 10-30 seconds per operation, on top of any file transfer Long, Meaningless Strings: Expect to be inundated with Job ID URLs, GUIDs, and LFNs lsh (lhcb shell) may help, if I ever have the time to write it will store all these items in a central DB with XML-RPC access and searchable by LCG identity

22. 16 th LHCb Software Week1 April 2004 LCG Key Links LCG LHCb-Help (ESUS) http://savannah.cern.ch/projects/lhcb-help Grid Operations Centre http://goc.grid-support.ac.uk