Oracle英文版培訓(xùn)課件之Data Guard Administration：L09-Switch-Fail

PerformingSwitchoverandFailoverObjectivesAftercompletingthislesson,youshouldbeabletodothefollowing:ExplainthedatabaserolesPerformaswitchoverPerformafailoverUseFlashbackDatabaseafterafailoverTypesofRolesinan

OracleDataGuardConfigurationTherearetwotypesofrolesinanOracleDataGuardconfiguration:Userrole:identifiesthegroupanddeterminestheprivilegesassignedtoauser.Databaserole:identifieswhatrole(primaryorstandby)thedatabaseplaysinaDataGuardconfiguration.SQL>SELECTdatabase_roleFROMv$database;

DATABASE_ROLE

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LOGICALSTANDBYRoleManagementServicesAdatabaseoperatesinoneoftwomutuallyexclusiverolesinaDataGuardconfiguration:Primaryrole:Thedatabaseisoperatingintheprimaryrole,andredotransportservicesareshippingredotothestandbydatabases.Standbyrole:Thedatabaseisoperatinginthestandbyrole,andlogapplyservicesareapplyingthearchivedredologstothestandbydatabase.Withrolemanagementservices,youcanchangetheserolesdynamically.RoleTransitions:SwitchoverandFailoverNotautomaticallyinvokedSwitchoverPlannedrolereversalUsedforOSorhardwaremaintenanceFailoverUnplannedrolereversalUsedinanemergencyMinimalornodatalossdependingonthe

data-protectionmodeFast-startfailovercanbeenabledforautomaticfailoverChoosingtheBestRoleTransitionOperationAreyouperformingaplannedroletransitionsothatyoucanperformhardwareorsoftwaremaintenanceonthesystemthatcurrentlyhoststheprimarydatabase?Switchovertobestavailablestandbydatabase.YesCanyouruncrashrecoverytorepairtheprimarydatabaseinatimelymanner?YesRepairprimarydatabase.NoNoFailovertobestavailablestandbydatabase.SwitchoverTransitionstherolesoftheprimaryandstandbydatabasesNoresettingoftheonlineredologsofthenewprimarydatabaseNodatalossSwitchover:BeforeStandby

databaseRead/write

transactionsPrimary

databaseSanFranciscoBostonOracleNetApplicationApplicationRead-onlyreportsSwitchover:AfterStandby

databaseRead/write

transactionsPrimary

databaseApplicationApplicationRead-onlyreportsSanFranciscoBostonOracleNetStandbyRedoLogsandSwitchoversStandbyredologsshouldbeconfiguredontheprimarydatabasetoeaseswitchovers.RedoshipmentRFSStandbyredologsOnlineredologsPrimarydatabaseStandbydatabaseStandbyredologsPreparingforaSwitchoverVerifythefollowinginpreparationfortheswitchoveroperation:networkconnectivitybetweentheprimaryandstandbylocations.PerformingaSwitchoverbyUsing

EnterpriseManagerSelectthedatabaseandclickSwitchover.PerformingaSwitchoverbyUsing

EnterpriseManagerClickYestoconfirm.PerformingaSwitchoverbyUsing

EnterpriseManagerPerformingaSwitchover

toaPhysicalStandbybyUsingSQLPerformthesestepsonlyifyouarenotusingtheDataGuardbroker.Ontheoriginalprimarydatabase:Verifythatitispossibletoperformaswitchoveroperation.Initiatetheswitchoveroperationontheprimarydatabase:Shutdownandrestarttheinstance.SQL>ALTERDATABASECOMMITTOSWITCHOVERTO2PHYSICALSTANDBY;PerformingaSwitchover

toaPhysicalStandbybyUsingSQLOntheoriginalphysicalstandbydatabase:VerifytheswitchoverstatusintheV$DATABASEview.Switchthephysicalstandbydatabaseroletotheprimaryrole.Ifthestandbydatabasewasopenedread-only,shutdownandrestartthenewprimarydatabase.Ifitwasnotopenedread-only,openthedatabase.Beginarchivinglogstothephysicalstandbydatabase.PerformingaSwitchover

toaLogicalStandbybyUsingSQLOntheoriginalprimarydatabase:Verifythatitispossibletoperformaswitchover.Preparetheprimarydatabasefortheswitchover:SQL>ALTERDATABASEPREPARETOSWITCHOVER2TOLOGICALSTANDBY;PerformingaSwitchover

toaLogicalStandbybyUsingSQLOntheoriginallogicalstandbydatabase:Preparethelogicalstandbydatabaseforswitchover:SQL>ALTERDATABASEPREPARETOSWITCHOVER2TOPRIMARY;PerformingaSwitchover

toaLogicalStandbybyUsingSQLOntheoriginalprimarydatabase:VerifytheswitchoverstatusinV$DATABASE.Switchtheprimarydatabasetothelogicalstandbydatabaserole:SQL>ALTERDATABASECOMMITTOSWITCHOVER2TOLOGICALSTANDBY;PerformingaSwitchover

toaLogicalStandbybyUsingSQLSQL>ALTERDATABASECOMMITTOSWITCHOVER2TOPRIMARY;SQL>ALTERSYSTEMARCHIVELOGCURRENT;Onthenewprimarydatabase(originallogicalstandbydatabase):VerifytheswitchoverstatusinV$DATABASE.Switchthelogicalstandbydatabasetotheprimarydatabaserole.Ensurethatallstandbydatabasesbeginreceivingredodata.PerformingaSwitchover

toaLogicalStandbybyUsingSQLOnthenewlogicalstandbydatabase:StartSQLApply.SQL>ALTERDATABASE2STARTLOGICALSTANDBYAPPLY;ConsiderationsWhenPerformingaSwitchovertoaLogicalStandbyDatabaseSwitchoveroperationdoesnotcauseashutdownoftheprimary.Thereisnoneedtoterminateusersessions,butterminationisrecommended.Logicalstandbydatabasemaynothavealldata.SituationsThatPreventaSwitchoverYoucannotperformaswitchoverinthefollowingsituations:Archivedredologfilesareunavailable.Point-in-timerecoveryisrequired.Productiondatabaseisnotopenandcannotbeopened.FailoverStandby

databasebecomesprimarydatabase.Read/write

transactionsOnlineredo

logsLocalarchivingSanFranciscoBostonArchivedredo

logsApplicationOnlineRedo

LogsLocalArchivingArchivedredo

logsPrimarydatabaseFailoverConsiderationsOldprimarydatabaseisnolongerpartoftheconfiguration.Datalossispossible.Failovershouldbeusedonlyinanemergency.Special-casefailover:activationofastandbyPerformingaFailoverbyUsing

EnterpriseManagerSelectthedatabaseandclickFailover.PerformingaFailoverbyUsing

EnterpriseManagerPerformingaFailoverbyUsing

EnterpriseManagerSelectthefailovertypeandclickYes.PerformingaFailoverbyUsing

EnterpriseManagerPerformingaFailover

toaPhysicalStandbyDatabaseThephysicalstandbydatabaseneedstobereinstated.PerformingaFailover

toaLogicalStandbyDatabaseThelogicalstandbydatabaseisnowtheprimarydatabase.Thephysicalstandbydatabaseisdisabled.PerformingaFailovertoa

PhysicalStandbyDatabasebyUsingSQLIdentifyandresolveanygapsinthearchivedredologfiles.Repeatstep1untilallgapsareresolved.Copyanyothermissingarchivedredologfiles.Initiatethefailoveroperationonthetargetstandbydatabase.Convertthephysicalstandbydatabasetotheprimaryrole.Completethetransitionofthestandbydatabasetotheprimarydatabaserole.(Optional)Backupthenewprimarydatabase.(Optional)Restorethefailedprimarydatabase.PerformingaFailovertoa

LogicalStandbyDatabasebyUsingSQLCopymissingredologstothelogicalstandbydatabase.Registerthemissingredologs:Ifitexists,registerthepartiallyfilledarchivelogfile.Ensurethatallredologfileshavebeenappliedtothenewprimarydatabase.SQL>ALTERDATABASEREGISTERLOGICAL2LOGFILE'filespec';SQL>SELECTAPPLIED_SCN,LATEST_SCN2FROMV$LOGSTDBY_PROGRESS;PerformingaFailovertoa

LogicalStandbyDatabasebyUsingSQLActivatethenewprimarydatabase:Enablearchivingofredologs.BeginSQLApplyoperationsonalllogicalstandbydatabases:SQL>ALTERDATABASEACTIVATE2LOGICALSTANDBYDATABASE3FINISHAPPLY;SQL>ALTERDATABASESTARTLOGICALSTANDBY2APPLYNEWPRIMARYdblink;ActivatingaStandbyDatabaseWhenyouareunabletofailover,youcanactivateastandbydatabasebyissuingoneofthefollowingcommands(dependingontheroleofthedatabase):SQL>ALTERDATABASEACTIVATE2LOGICALSTANDBYDATABASE;SQL>ALTERDATABASEACTIVATE2PHYSICALSTANDBYDATABASE;RestoringDatabasesAfteraRoleTransitionAdditionalstepsmaybeneededtorestoreyourdisaster-recoverysolutionafteraroletransition:Databasesmaybedisabled,butarenotremovedfromthebrokerconfiguration.Reenablebrokermanagementofthedatabases:ReinstatedatabasesusingtheREINSTATE

DATABASEcommandorthroughEnterpriseManager.Re-createdatabasesfromacopyoftheprimarydatabaseandreenablethedatabase