» sap hana interview questions – slt replication.pdf

5/6/2015 SAPHANAInterviewQuestionsSLTReplication

http://saphanatutorial.com/saphanainterviewquestionssltreplication/ 1/17

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TopicIndexSAPHANAInterviewQuestionsArchitectureandOverviewSAPHANAModelingSAPHANASLTReplicationSAPHANAStudioSAPHANAXS+HadoopInterviewQuestions

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Qs.Whatarethedifferenttypesofreplicationtechniques?

Thereare3typesofreplicationtechniques:1.SAPLandscapeTransformation(SLT)2.SAPBusinessObjectsDataServices(BODS)3.SAPHANADirectExtractorConnection(DXC)

Note:ThereisonemorereplicationtechniquecalledSybasereplication.ItwaspartofinitialofferingforHANAreplication,butnotpositioned/supportedanymoreduetolicensingissuesandcomplexityandmostlybecauseSLTprovidesthesamefeatures.

Qs.WhatisSLT?TheSAPLandscapeTransformation(LT)ReplicationServeristheSAPtechnologythatallowsustoloadandreplicatedatainrealtimefromSAPsourcesystemsandnonSAPsourcesystemstoanSAPHANAenvironment.

TheSAPLTReplicationServerusesatriggerbasedreplicationapproachtopassdatafromthesourcesystemtothetargetsystem.

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Qs.WhatistheadvantageofSLTreplication?Advantages:

1. SAPLTusestriggerbasedapproach.Triggerbasedapproachhasnomeasureableperformanceimpactinsourcesystem.2. Itprovidestransformationandfilteringcapability.3. Itallowsrealtime(andscheduled)datareplication,replicatingonlyrelevantdataintoHANAfromSAPandnonSAPsourcesystems.4. ItisfullyintegratedwithHANAStudio.5. ReplicationfrommultiplesourcesystemstooneHANAsystemisallowed,alsofromonesourcesystemtomultipleHANAsystems.

Qs.IsitpossibletouseareplicationformultiplesourcesandtargetSAPHANAsystems?Yes,theSAPLTReplicationServersupportsboth1:NreplicationandandN:1replication.

MultiplesourcesystemcanbeconnectedtooneSAPHANAsystem.OnesourcesystemcanbeconnectedtomultipleSAPHANAsystems.Limitedto1:4only.

Qs.Isthereanyprerequisitebeforecreatingtheconfigurationandreplication?ForSAPsourcesystems:

1. DMISaddonmustbeinstalledinSLTreplicationserver.2. AnRFCconnectionbetweentheSAPsourcesystemandtheSAPLTReplicationServerhastobeestablished.



3. UserforRFCconnectionmusthavetheroleIUUC_REPL_REMOTEassigned.4. DonotuseaDDICuserforRFCconnection.

FornonSAPsourcesystems:

1. DMISaddonisnotrequired.2. AdatabaseuserhastobecreatedwithappropriateauthorizationsinadvanceandestablishthedatabaseconnectionbyusingtransactionDBCOintheSAPLTReplicationServer.3. EnsurethedatabasespecificlibrarycomponentsfortheSAP7.20RELorEXTkernelareinstalledintheSAPLTReplicationServer.

Qs.WhatisConfigurationandMonitoringDashboard?ItisanapplicationthatrunsonSLTreplicationservertospecifyconfigurationinformation(suchassourcesystem,targetsystem,andrelevantconnections)sothatdatacanbereplicated.

Itcanalsouseittomonitorthereplicationstatus(transactionLTR).

StatusYellow:Itmayoccurduetotriggerswhicharenotyetcreatedsuccessfully.

StatusRed:Itmayoccurifmasterjobisaborted(manuallyintransactionSM37).

Qs.Whatisadvancedreplicationsettings(transactionIUUC_REPL_CONT)?TheAdvancedSettings(transactionIUUC_REPL_CONT)allowsyoutodefineandchangevarioustablesettingsforaconfigurationsuchas:

PartitioningandstructurechangesfortargettablesinHANATablespecifictransformationandfilterrulesAdjustingthenumberofjobs(andreadingtype)toacceleratetheload/replicationprocess

Qs.WhatisLatency?Itisthelengthoftimetoreplicatedata(atableentry)fromthesourcesystemtothetargetsystem.

Qs.Whatisloggingtable?Atableinthesourcesystemthatrecordsanychangestoatablethatisbeingreplicated.ThisensuresthatSLTreplicationservercanreplicatethesechangestothetargetsystem.

Qs.WhatareTransformationrules?ArulespecifiedintheAdvancedReplicationsettingstransactionforsourcetablessuchthatdataistransformedduringthereplicationprocess.Exampleyoucanspecifyruleto

ConvertfieldsFillemptyfieldsSkiprecords

Qs.Whathappenswhenyousetupanewconfiguration?WhenanewconfigurationintheSAPLTReplicationServeriscreated,thedatabaseconnectionisautomaticallycreatedalongwithaschemaGUIDandMasstransferid(MT_ID).AschemaGUIDensuresthatconfigurationswiththesameschemanamecanbecreated.TheMasstransferIDisusedinthenamingofSLTjobsandthesystemcanuniquelyidentifyaschema.ThemappingofmasstransferIDsandrelatedschemaarestoredintheSLTcontroltableDMC_MT_HEADERintheSAPLTReplicationServer.

Qs.Whatarethejobsinvolvedinreplicationprocess?Followingjobsareinvolvedinreplicationprocess:

1. MasterJob(IUUC_MONITOR_)2. MasterControllingJob(IUUC_REPLIC_CNTR_)3. DataLoadJob(DTL_MT_DATA_LOAD__)4. MigrationObjectDefinitionJob(IUUC_DEF_MIG_OBJ_)5. AccessPlanCalculationJob(ACC_PLAN_CALC__)

Qs.Whatisthepurposeofmasterjob(IUUC_MONITOR_)?Every5seconds,themonitoringjobchecksintheSAPHANAsystemwhethertherearenewtasksand,ifso,triggersthemastercontroljobs.Italsodeletestheprocessedentries(tasks)fromtableRS_ORDERandwritesstatisticsentriesintotableRS_STATUS(intherelevantschemaintheSAPHANAsystem).

Qs.Whatisthepurposeofmastercontrollerjob(IUUC_REPLIC_CNTR_)?Thisjobisscheduledondemandandisresponsiblefor:

CreatingdatabasetriggersandloggingtableinthesourcesystemCreatingsynonymsWritingnewentriesinadmintablesinSLTserverwhenanewtableisloaded/replicated



Qs.WhatisthepurposeofDataLoadJob(DTL_MT_DATA_LOAD__)?Thisjobshouldalwaysbeactive.Ifthejobdoesnotcompletesuccessfully,themastercontrollerjobrestartsit.

Thisjobisresponsiblefor:

Loadingdata(load)Replicatingdata(replication)ChangingstatusflagforentriesincontroltablesintheSAPLTReplicationServer

Qs.WhatisthepurposeofMigrationObjectDefinitionJob(IUUC_DEF_MIG_OBJ_)?Thisjobdefinesthemigrationobjectofaspecifictable(thatyouchoosetoload/replicate),whichisthefundamentalobjectforLTreplication.Themigrationobjectdefinitionshouldnormallybequitefastforalltables.

Qs.WhatisthepurposeofAccessPlanCalculationJob(ACC_PLAN_CALC__)?Thisjobcalculatestheaccessplanofaspecifictable(thatyouchoosetoload/replicate),andtheaccessplanisusedfordataloadorreplication.Theaccessplanisalsoafundamentalobjectforthereplication.Foranormalsizedtable,accessplancalculationshouldfinishquitequickly(lessthan1minute)whilelargetablesmighttakeuptoseveralhourstofinish.

Qs.WhatistherelationbetweenthenumberofdatatransferjobsintheconfigurationsettingsandtheavailableBGDworkprocesses?Eachjoboccupies1BGDworkprocessesinSLTreplicationserver.Foreachconfiguration,theparameterDataTransferJobsrestrictsthemaximumnumberofdataloadjobforeachmasstransferID(MT_ID).

AmasstransferIDrequiresatleast4backgroundjobstobeavailable:

OnemasterjobOnemastercontrollerjobAtleastonedataloadjobOneadditionaljobeitherformigration/accessplancalculation/tochangeconfigurationsettingsinConfigurationandMonitoringDashboard.

Qs.Ifyousettheparameterdatatransferjobsto04inaconfigurationSCHEMA1,amasstransferID001isassigned.Thenwhatjobsshouldbeinthesystem?

1Masterjob(IUUC_MONITOR_SCHEMA1)1MasterControllerjob(IUUC_REPL_CNTR_001_0001)Atmost4paralleljobsforMT_ID001(DTL_MT_DATA_LOAD_001_01/~02/~03/~04)

Qs.WhathappensaftertheSLTreplicationisover?TheSLTreplicationservercreates1user,4roles,2storedproceduresand8tables.

1User1Privilege4Roles

1. _DATA_PROV2. _POWER_USER3. _USER_ADMIN4. _SELECT

2Storedprocedures1. RS_GRANT_ACCESS2. RS_REVOKE_ACCESS

8Tables1. DD02L2. DD02T3. RS_LOG_FILES4. RS_MESSAGES5. RS_ORDER6. RS_ORDER_EXT7. RS_SCHEMA_MAP8. RS_STATUS

Qs.Whatarethedifferentreplicationscenarios?Differentreplicationscenariosare:Load,Replicate,Stop,SuspendandResume.Load:Startsaninitialloadofreplicationdatafromthesourcesystem.Theprocedureisaonetimeevent.Afteritiscompleted,furtherchangestothesourcesystemdatabasewillnotbereplicated.Fortheinitialloadprocedure,neitherdatabasetriggersnorloggingtablesarecreatedinthesourcesystem.Defaultsettingsusereadingtype3(DB_SETGET)withupto3backgroundjobsinparalleltoloadtablesinparallelorsubsequentlyintotheHANAsystem.



Replicate:Combinesaninitialloadprocedureandthesubsequentreplicationprocedure(realtimeorscheduled).Beforetheinitialloadprocedurewillstart,databasetriggerandrelatedloggingtablearecreatedforeachtableinthesourcesystemaswellasinSLTreplicationserver.

Stop:Stopsanycurrentloadorreplicationprocessofatable.Thestopfunctionwillremovethedatabasetriggerandrelatedloggingtablescompletely.Onlyusethisfunctionifyoudowanttocontinueaselectedtableotherwiseyoumustinitiallyloadthetableagaintoensuredataconsistency.

Suspend:Pausesatablefromarunningreplication.Thedatabasetriggerwillnotbedeletedfromthesourcesystem.Therecordingofchangeswillcontinueandrelatedinformationisstoredintherelatedloggingtablesinthesourcesystem.Ifyoususpendtablesforalongtimethesizeofloggingtablesmayincreaseandadjustthetablespaceifrequired.

Resume:Restartstheapplicationforasuspendedtable.Theprevioussuspendedreplicationwillberesumed(nonewinitialloadrequired).

Qs.WhathappensifthereplicationissuspendedforalongperiodoftimeorsystemoutageofSLTorHANAsystem?Thesizeoftheloggingtablesincreases.

Qs.Howtoavoidunnecessarylogginginformationfrombeingstored?Pausethereplicationbystoppingtheschemarelatedjobs.

Qs.WillthetablesizeinSAPHANAdatabaseandinthesourcesystemthesame?No.AsHANAdatabasesupportscompression,thetablesizeinSAPHANAmaybedecreased.

Qs.Whentogofortablepartitioning?IfthetablesizeinHANAdatabaseexceeds2billionrecords,splitthetablebyusingportioningfeaturesbyusingAdvancedreplicationsettings(transactionIUUC_REPL_CONT,tabpageIUUC_REPL_TABSTG).

Qs.Wheredoyoudefinetransformationrules?ByusingAdvancedreplicationsettings(transactionIUUC_REPL_CONT,tabpageIUUCASSRULEMAP)

Qs.ArethereanyspecialconsiderationsifthesourcesystemisnonSAPsystem?TheconceptoftriggerbasedreplicationisactuallymeantforSAPsourcesystems.IncaseofnonSAPsystem,followingpointsshouldbekeptinmind:

TherewillbeadatabaseconnectionbetweennonSAPsourceandSLTsysteminsteadofRFC.SourcemusthaveprimarykeyTablesDD02L,DD02Twhichcontainsmetadataarejustinitiallyloadedbutnotreplicated.ThereadmodulesresideonSLTsystem.Tableswithdatabasespecificformatsmayneedtransformationrulesbeforetheyarereplicated.OnlySAPsupporteddatabasesaresupportedasnonSAPsourcesystems.

Qs.DoesSLTforSAPHANAsupportdatacompressionlikeSAPHANAdatabase?Yes,thisisautomaticallycoveredbytheRFCconnectionusedfordatareplicationfromtheSAPsourcesystem.

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