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Interplay between LCG and ALICE Environment

Interplay between LCG and ALICE Environment. Patricia Méndez Lorenzo CERN IT-ED-PSS ALICE-CIEMAT Meeting Madrid 4 th May 2006. Introduction and Outlook. After seeing the ALICE Computing Model, now we will see the interplay with LCG The central point of the presentation: VOBOX

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Interplay between LCG and ALICE Environment

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  1. Interplay between LCG and ALICE Environment Patricia Méndez Lorenzo CERN IT-ED-PSS ALICE-CIEMAT Meeting Madrid 4th May 2006

  2. Introduction and Outlook • After seeing the ALICE Computing Model, now we will see the interplay with LCG • The central point of the presentation: VOBOX • Now we will see: • ◘ General introduction to the VOBOX service • ◘ How ALICE uses it • ◘ How ALICE-LCG works together to set them up • ➸ Requirements • ➸ Current Status FZK 20th October Patricia Mendez Lorenzo

  3. 1st PART: GENERAL OUTLOOK OF THE VOBOX SERVICE FZK 20th October Patricia Mendez Lorenzo

  4. General Introduction to the VOBOX Service • New LCG Service (from v2.6.0) • Motivation: • ◘ Several experiments run service jobs in the production sites • ➸In some cases using the Fork Jobmanager in the gatekeeper node • ◘ The BaseLine service workgroup identified the need of the experiments to run specific services in the sites • ◘ The solution has to be acceptable for experiments and for the sites • Solution: • ◘ A separate service where experiments can run their agents and experiments • ➸Specific agents not provided by the LCG middleware FZK 20th October Patricia Mendez Lorenzo

  5. General Introduction to the VOBOX Service (cont) • General Characteristics for any VOBOX: • ◘ Only sgm users of each VO have access to the node • ◘ From LCGv.7.0 it run the UI service inside (asked by ALICE and provided for all experiments) • ◘ It provides direct access to the software area • ➸Area mounted and accessible in the filesystem • ➸VO_ALICE_SW_DIR variable mandatory • ◘ Contains a GSISSH server (port 1975) • ➸ssh connection authorized through user proxies • ◘ Proxy renewal service included • ◘ If needed GSSKLOG client • ➸Needed if the software area is placed in AFS • ◘ It runs a local GRIS • ➸ The Service must be published in the information system FZK 20th October Patricia Mendez Lorenzo

  6. General Introduction to the VOBOX Service (cont) • General Requirements for any VOBOX: • ◘ OS: Scientific Linux (usually) • ◘ WN type host + experiment specific requirements • ◘ Outbound connectivity • ➸It is a UI (globus range 20000-25000) • ◘ Inbound connectivity • ➸As for a CE plus experiment requirements • ◘ Access to local accounts via gsissh (port 1975) • ◘ Write access to the software area • ◘ At this moment a gridftp server is included (port 2811) FZK 20th October Patricia Mendez Lorenzo

  7. 2nd PART: HOW DOES ALICE USE THE VOBOX FZK 20th October Patricia Mendez Lorenzo

  8. Task Queue LFC File Catalogue Interfacing AliEn and LCG ALICE SC3 layout LCG site (T1) ALICE Layout in terms of LCG WN LCG CE User (Production Manager) VO-Box (UI) RB (external) SE (local) CElist T1 ENTRY DOOR T2 VO-BOX (UI) CeList T2 LCG WORLD ALICE Central Services T2 VO-BOX (UI) CeList T2 FZK 20th October Patricia Mendez Lorenzo

  9. General Outlook of the Services • 1. CENTRAL ALICE SERVICES • ◘ OUTSIDE of the LCG environment • ➸Central TQ, central FC, VOMS, FTD • ◘ Their experts take care of them • 2. LCG SERVICES USED BY ALICE • ◘All of them!: RB/WMS, VOMS, FTS/SRM, LFC • ◘ No experience up to now with dCACHE and DPM • 3. ALICE SITE VOBOX SERVICES • ◘ Specific ALICE site services all run in VOBOXES • ◘ Supported together by LCG and ALICE experts • ➸PackMan, MonaLisa, Site Computing Agent, Storage Adaptor, xrootd, site proxy, proofd, agent monitoring service FZK 20th October Patricia Mendez Lorenzo

  10. Outlook of ALICE Site services • PackMan • ◘ It distributes, installs and configures the software needed by ALICE jobs • ◘ Includes versioning and test tools • ◘ Integrated with the TQ central service, it takes care of the matchmaking • ◘ If a job needs a certain software to run, this service automatically install it before pulling it from the TQ • ◘ It is a complex and reliable service needed by the ALICE architecture • ◘ It writes the software under VO_ALICE_SW_DIR • ➸It must therefore run in the VOBOX to access this area FZK 20th October Patricia Mendez Lorenzo

  11. Outlook of ALICE Site services • MonAlisa • ◘ It monitors the job status, the storage and the traffic • ◘ It includes specific ALICE monitoring • ◘ ALICE would like to have it as BS service following other experiment initiatives • ◘ It is installed in the VOBOX because: • ➸It runs specific LCG test suites which must be executed from the VOBOX (monitoring of the VO-BOX itself) • ➸ If a previous local aggregation is performed it will minimize the monitoring traffic FZK 20th October Patricia Mendez Lorenzo

  12. Outlook of ALICE Site services • Site Computing Agent • ◘ Interfaces different WMS (LCG, OSG, etc) • ◘ It performs the matchmaking with the ALICE TQ • ◘ This service in principle could be run centrally but scaling and size problems of the CERN ALICE installation would appear • Agent Monitoring Service • ◘ Control of all VOBOX services • ◘ As long as the VOBOX exists, the service will run there FZK 20th October Patricia Mendez Lorenzo

  13. Outlook of ALICE Site services • Storage Adaptor • ◘ Handles the communication with LFC to translate GUID to TURL/SURL • ◘ Builds the TURL • ◘ Can act as a volume manager • ◘ Starts up xrootd services • ◘ Handles communication with FTD • ◘ Monitor site storage configuration • ◘ It must run in the VOBOX because • ➸To avoid communication with the central service (catalog) • ➸ Need to communicate with the local LFC • ➸ Need to be local to start xrootd and to monitorthe storage FZK 20th October Patricia Mendez Lorenzo

  14. Outlook of ALICE Site services • Site Proxy • ◘ Communication between job agent and central services in case WN do not have incoming/outgoing connectivity • ◘ It runs in the VOBOX because • ➸Needs to communicate with the local services • ➸ Essential to handle local VO-Specific services • Proofd • ◘ Handle communication between local master and workers when using proof on wide area • ◘ It runs in the VOBOX because: • ➸Needs to communicate with the local WN • ➸ At this moment is part of xrootd FZK 20th October Patricia Mendez Lorenzo

  15. Outlook of ALICE Site services • Xrootd • ◘ Posix I/O • ◘ Insulates application from local storage systems • ◘ Efficient handling of storage • ◘ Handles user-level file authorization • ◘ It runs in the VOBOX because: • ➸It needs to communicate with the local SE • ◘ An official requirement of ALICE to include it in the middleware ongoing FZK 20th October Patricia Mendez Lorenzo

  16. 3rd PART: SETTING THE VOBOX UP FZK 20th October Patricia Mendez Lorenzo

  17. Specific ALICE Requirements • Document: “VOBOX Security and Operations Questionnaires v-0.5” • LCG Configuration requirements • ◘ Full LCG UI (included in default) • ◘ FTS client (Perl APIs) (included in the UI) • ◘ lcg-infosites (included in the UI) • ◘ Local LFC Server with ALICE access • ◘ Access to the local RB (default gdrb11.cern.ch) • ALICE Configuration • ◘ The ALICE experts will take care of the installation • ◘ The site manager should take care of the ALICE ports • ◘ The VOBOX must be Alice specific used only • BACKUP • ◘ Local directory of the alicesgm user • ◘ /opt/vobox directory FZK 20th October Patricia Mendez Lorenzo

  18. Setting up a new VOBOX • You are providing a VOBOX for ALICE: • ◘ Get a host certificate for the machine and send me the subject back • ➸Registration in the myproxy server at CERN • ◘ Perform the LCG VOBOX installation and configuration • http://goc.grid.sinica.edu.tw/gocwiki/VO-box_HowTo • ◘ As site manager, configure the connection requirements of ALICE following VOBOX questionnaire document • ◘ Announce the alice-lcg-task-force@cern.ch list that the VOBOX is ready for testing • ◘ Now we will test it from the LCG point of view and then open it to the ALICE installation and configuration • http://alien.cern.ch/twiki/bin/view/AliEn/HowToInstallLcgVoBox FZK 20th October Patricia Mendez Lorenzo

  19. Conclusions • ◘ ALICE has a well defined infrastructure of Services included in the VOBOX • ◘ This node is the ALICE entry door to the LCG • ➸Mandatory to provide for Alice exclusive use only • ◘ At this moment more than 20 VOBOXES in production • ➸No site is opened until the full configuration of the VOBOX • ◘ Well defined infrastructure of deployment and testing • ◘ Before installing the VOBOX read the documentation: • ➸ALICE VOBOX Requirements • ➸ VOBOX installation • ➸ AliEn installation in the VOBOX • ◘ You have a well defined set of persons providing you support from ALICE and LCG FZK 20th October Patricia Mendez Lorenzo

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