Interplay between LCG and ALICE Environment
description
Transcript of Interplay between LCG and ALICE Environment
INFSO-RI-508833
Enabling Grids for E-sciencE
www.eu-egee.org
Interplay between LCG and ALICE Environment
Patricia Méndez Lorenzo
CERN IT-ED-PSS
ALICE-CIEMAT MeetingMadrid4th May 2006
FZK 20th October Patricia Mendez Lorenzo
Enabling Grids for E-sciencE
INFSO-RI-508833
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
Enabling Grids for E-sciencE
INFSO-RI-508833
1st PART: GENERAL OUTLOOK OF THE VOBOX SERVICE
FZK 20th October Patricia Mendez Lorenzo
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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 sitesSolution: ◘ A separate service where experiments can run their agents and experiments ➸ Specific agents not provided by the LCG middleware
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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
Enabling Grids for E-sciencE
INFSO-RI-508833
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)
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INFSO-RI-508833
2nd PART: HOW DOES ALICE USE THE VOBOX
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Interfacing AliEn and LCG
ALICE SC3 layout
User(ProductionManager)
LCG site (T1)
LCG CEWN
VO-Box (UI)
TaskQueue
LFC FileCatalogue
RB (external)CElist
T1 SE
(local)
T2
VO-BOX
(UI)
CeList T2
T2
VO-BOX
(UI)
CeList T2
ALICE Layout in terms of LCG
ALICE Central
Services LCG WORLD
ENTRY DOOR
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Enabling Grids for E-sciencE
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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 them2. LCG SERVICES USED BY ALICE
◘ All of them!: RB/WMS, VOMS, FTS/SRM, LFC◘ No experience up to now with dCACHE and DPM3. 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
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INFSO-RI-508833
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
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INFSO-RI-508833
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
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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
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Enabling Grids for E-sciencE
INFSO-RI-508833
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 monitor the storage
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Enabling Grids for E-sciencE
INFSO-RI-508833
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
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INFSO-RI-508833
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
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Enabling Grids for E-sciencE
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3rd PART: SETTING THE VOBOX UP
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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 onlyBACKUP◘ Local directory of the alicesgm user◘ /opt/vobox directory
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INFSO-RI-508833
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 [email protected] 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
Enabling Grids for E-sciencE
INFSO-RI-508833
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