简介：ThechallengeofLHCcomputing,withdataratesintherangeofseveralPB/year,requiresthedevelopmentofGRIDtechnologies,tooptimizetheexploitationofdistributedcomputingpowerandtheauthomaticaccesstodistributeddatastorage.IntheframeworkoftheEU-DataGridproject,theALICEexperimentisoneoftheselectedtestapplicationsfortheearlydevelopmentandimplementationofGRIDServices.Presently,about15ALICEsitesaremakinuseofavailableGRIDtoolsandalargescaletestproductioninvolving9ofthemwascarriedoutwithoursimulationprogram.Resultsarediscussedindetail,aswellasfutureplans.

简介：Since1998,theALICEexperimentandtheCERN/ITdivisionhavejointlyexecutedseverallarge-scalehighthroughputdistributedcomputingexercises:theALICEdatachallenges.ThegoalsoftheseregularexercisesaretotesthardwareandsoftwarecomponentsofthedataacqusitionandcomputingsystemsinrealisticconditionsandtoexecuteanearlyintegrationoftheoverallALICEcomputinginfrastructure.ThispaperreportsonthethirdALICEDataChallenge(ADCIII)thathasbeenperformedatCERNfromJanuarytoMarch2001.ThedatausedduringtheADCⅢaresimulatedphysicsrawdataoftheALICETPC,producedwiththeALICEsimulationprogramAliRoot.ThedataacquisitionwasbasedontheALICEonlineframeworkcalledtheALICEDataAcquisitionTestEnvironment(DATE)system.Thedataaftereventbuilding,werethenformattedwiththeROOTI/OpackageandadatacataloguebasedonMySQlwasestablished.TheMassStorageSystemusedduringADCIIIisCASTOR.Differentsoftwaretoolshavebeenusedtomonitortheperformances,DATEhasdemonstratedperformancesofmorethan500MByte/s.Anaggregatedatathroughputof85MByte/swassutainedinCASTORoverseveraldays.Thetotalcollecteddataamountsto100TBytesin100.00files.

简介：TheALICEexperiment[1]attheLargeHadronCollider(LHC)atCERNwilldetectupto20,000particlesinasinglePb-Pbeventresultinginadatarateof-75MByte/event,Theeventrateislimitedbythebandwidthofthedatastoragesystem.Higherratesarepossiblebyselectinginterestingeventsandsubevents(HighLeveltrigger)orcompressingthedataefficientlywithmodelingtechniques.Bothrequireafastparallelpatternrecognition.OnepossiblesolutiontoprocessthedetectordataatsuchratesisafarmofclusteredSMPnodes,basedonoff-the-shelfPCs,andconnectedbyahighbandwidt,lowlatencynetwork.

简介：TheALICETriggerandDataAcquisition(TRG/DAQ)Systemisrequiredtosupportanaggregateeventbuildingbandwidthofupto4GByte/sandastoragecapabilityofupto1.25GByte/stomassstorage.Thesystemhasbeendecomposedinasetofhardwareandsoftwarecomponentsandprototypesofthesecomponentsarebeingdeveloped.Itisnecessarytoveritythesystemdesign,itscapabilitytoreachtheexpectedbehaviorandthetargetperformances,discoverpossiblebottlenecksandwaystocorrectforthem,andexplorealternativealgorithmsandnewarchitectures.ToachievethisthecompleteTRG/DAQsystemhasbeenformallyspecified.andtheverificationoftheexpectedbehaviorhasbeenperformedthroughtheexecutionofthespecification,Twotoolswereusedforthis.Foresight,andPtolemy.