Duplicating a Database with Recovery Manager.docx

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Duplicating a Database with Recovery Manager.docx

DuplicatingaDatabasewithRecoveryManager

ThischapterdescribeshowtousetheDUPLICATEcommandtocreateaduplicatedatabasefortestingpurposes.Thischaptercontainsthesetopics:

∙CreatingaDuplicateDatabase:

Overview

∙GeneratingFilesfortheDuplicateDatabase

∙PreparingtheAuxiliaryInstanceforDuplication:

BasicSteps

∙CreatingaDuplicateDatabaseonaLocalorRemoteHost

∙DatabaseDuplicationExamples

SeeAlso:

OracleDataGuardConceptsandAdministrationtolearnhowtocreateastandbydatabasewiththeDUPLICATEcommand

CreatingaDuplicateDatabase:

Overview

YoucanusetheRMANDUPLICATEcommandtocreateaduplicatedatabasefromtargetdatabasebackupswhilestillretainingtheoriginaltargetdatabase.Theduplicatedatabasecanbeidenticaltotheoriginaldatabaseorcontainonlyasubsetoftheoriginaltablespaces.

Aduplicatedatabaseisacopyofatargetdatabasethatyoucanrunindependentlyforavarietyofpurposes.Forexample,youcanuseitto:

∙Testbackupandrecoveryprocedures

∙Exportdatasuchasatablethatwasinadvertentlydroppedfromtheproductiondatabase,andthenimportitbackintotheproductiondatabase

Forexample,youcanduplicatetheproductiondatabaseonhost1tohost2,andthenusetheduplicatedatabaseonhost2topracticerestoreandrecoveryscenarioswhiletheproductiondatabaseonhost1continuesasusual.

Aduplicatedatabaseisdistinctfromastandbydatabase,althoughbothtypesofdatabasesarecreatedwiththeDUPLICATEcommand.Astandbydatabaseisacopyoftheprimarydatabasethatyoucanupdatecontinuallyorperiodicallywitharchivedlogsfromtheprimarydatabase.Iftheprimarydatabaseisdamagedordestroyed,thenyoucanperformfailovertothestandbydatabaseandeffectivelytransformitintothenewprimarydatabase.Aduplicatedatabase,ontheotherhand,cannotbeusedinthisway:

itisnotintendedforfailoverscenariosanddoesnotsupportthevariousstandbyrecoveryandfailoveroptions.

SeeAlso:

OracleDataGuardConceptsandAdministrationtolearnhowtocreateastandbydatabasewiththeDUPLICATEcommand

HowRecoveryManagerDuplicatesaDatabase

Topreparefordatabaseduplication,youmustfirstcreateanauxiliaryinstanceasdescribedin"PreparingtheAuxiliaryInstanceforDuplication:

BasicSteps".Fortheduplicationtowork,youmustconnectRMANtoboththetarget（primary）databaseandanauxiliaryinstancestartedinNOMOUNTmode.

Youmusthaveatleastoneauxiliarychannelallocatedontheauxiliaryinstance.Theprincipalworkoftheduplicationisperformedbytheauxiliarychannel,whichstartsaserversessionontheduplicatehost.Thischannelthenrestoresthenecessarybackupsoftheprimarydatabase,usesthemtocreatetheduplicatedatabase,andinitiatesrecovery.

SolongasRMANisabletoconnecttotheprimaryandauxiliaryinstances,theRMANclientcanrunonanymachine.However,allbackupsandarchivedlogsusedforcreatingandrecoveringtheduplicatedatabasemustbeaccessiblebytheserversessionontheduplicatehost.Iftheduplicatehostisnotthesameastheprimaryhost,thenyoumustmakebackupsondiskontheprimaryhostavailabletotheduplicatehostwiththesamefullpathnameasintheprimarydatabase.Whenusingdiskbackups,youcanaccomplishthisgoalinanyofthefollowingways:

∙Manuallytransferthebackupsfromtheprimaryhosttotheremotehosttoanidenticalpath.

∙Manuallytransferthebackupsfromtheprimaryhosttotheremotehosttoanewpath,andthenruntheCATALOGcommandtoaddthesecopiestotheRMANrepository.

∙UseNFSorshareddisksandmakesurethatthesamepathisaccessibleintheremotehost.

Whenusingtapebackups,youmustmakethetapescontainingthebackupsaccessibletotheremotenode,eitherbyphysicallymovingthetapetotheremotehostorbymeansofanetworktapeserver.

Aspartoftheduplicatingoperation,RMANautomatesthefollowingsteps:

∙Createsacontrolfilefortheduplicatedatabase

∙Restoresthetargetdatafilestotheduplicatedatabaseandperformsincompleterecoverybyusingallavailableincrementalbackupsandarchivedlogs

∙Shutsdownandstartstheauxiliaryinstance（referto"Task4:

StarttheAuxiliaryInstance"forissuesrelatingtoclient-sideversusserver-sideinitializationparameterfiles）

∙OpenstheduplicatedatabasewiththeRESETLOGSoptionafterincompleterecoverytocreatetheonlineredologs（exceptwhenrunningDUPLICATE...FORSTANDBY,inwhichcaseRMANdoesnotopenthedatabase）

∙Generatesanew,uniqueDBIDfortheduplicatedatabase（exceptwhenyoucreateastandbydatabasewithDUPLICATE...FORSTANDBY,inwhichcaseRMANdoesnotcreateauniqueDBID）

Duringduplication,RMANmustperformincompleterecoverybecausetheonlineredologsinthetargetarenotbackedupandcannotbeappliedtotheduplicatedatabase.ThefarthestthatRMANcangoinrecoveryoftheduplicatedatabaseisthemostrecentredologarchivedbythetargetdatabase.

SeeAlso:

OracleDataGuardConceptsandAdministrationtolearnhowtocreateastandbydatabasewithRMAN

DatabaseDuplicationOptions

Whenduplicatingadatabase,youhavethefollowingoptions:

∙YoucanruntheDUPLICATEcommandwithorwithoutarecoverycatalog

∙Youcanskipread-onlytablespaceswiththeSKIPREADONLYclause.Read-onlytablespacesareincludedbydefault.Ifyouomitthem,thenyoucanaddthemlater.

∙YoucanexcludetablespacesfromtheduplicatedatabasewiththeSKIPTABLESPACEclause.YoucanexcludeanytablespaceexcepttheSYSTEMtablespaceortablespacescontainingrollbackorundosegments.

∙Youcancreatetheduplicatedatabaseinanewhost.Ifthedirectorystructureisthesameonthenewhost,thenyoucanspecifytheNOFILENAMECHECKoptionandreusethetargetdatafilefilenamesfortheduplicatedatafiles.

∙YoucanduplicateatargetdatabaseonatraditionalfilesystemtoanASMorOracleManagedFileslocation.

∙Youcanrecovertheduplicatedatabasetoapastpointintime,usingusetheSETUNTILcommandorDUPLICATE...UNTILcommand.Bydefault,theDUPLICATEcommandcreatestheduplicatedatabasebyusingthemostrecentbackupsofthetargetdatabaseandthenperformsrecoverytothemostrecentconsistentpointcontainedintheincrementalbackupsandarchivedlogs.

∙Youcanregistertheduplicatedatabaseinthesamerecoverycatalogasthetargetdatabase.ThisoptionispossiblebecauseRMANgivestheduplicatedatabaseanew,uniqueDBIDduringduplication.

Note:

Ifyoucopythetargetdatabasebymeansofoperatingsystemutilities,thentheDBIDofthecopieddatabaseremainsthesameastheoriginaldatabase.Toregisterthecopydatabaseinthesamerecoverycatalogwiththeoriginal,youmustchangetheDBIDwiththeDBNEWIDutility（refertoOracleDatabaseUtilities）.

∙Insomecases,youcansettheduplicatedatabaseDB_NAMEdifferentlyfromthetargetdatabaseDB_NAME.Morespecifically,iftheduplicatedatabaseexistsinthesameOraclehomeasthetarget,thentheDB_NAMEinitializationparametermustbedifferent.IftheduplicatedatabaseisinadifferentOraclehomefromthetargetdatabase,thentheDB_NAMEsettingfortheduplicatedatabasemustbeuniqueamongdatabasesinitsOraclehome.Thisistruewhetherornottheduplicatedatabaseisonthesamehostasthetarget.

DuplicatingaDatabase:

PrerequisitesandRestrictions

RMANduplicationinvolvesanumberofprerequisites,restrictions,andcaveats.ReviewtherestrictionssectionoftheDUPLICATEcommandintheOracleDatabaseRecoveryManagerReferenceforacompletelist.

GeneratingFilesfortheDuplicateDatabase

Whenduplicatingadatabase,RMANcreatestherequireddatabasefiles.Thissectiondescribesthesestagesoffilecreation:

∙CreatingtheDuplicateControlFiles

∙CreatingtheDuplicateOnlineRedoLogs

∙RenamingDatafilesWhenDuplicatingaDatabase

CreatingtheDuplicateControlFiles

TheDUPLICATEcommandcreatesthecontrolfilesbyusingthenameslistedintheinitializationparameterfileoftheauxiliaryinstance.Whenchoosingnamesfortheduplicatedatabasecontrolfiles,makesurethatyousettheinitializationparametersettingscorrectlysothatyoudonotoverwritetheproductionfilesatthetargetdatabase.

CreatingtheDuplicateOnlineRedoLogs

Table 11-1liststheoptionsforcreatingthenamesoftheduplicateonlineredologs.Theoptionsappearintheorderofprecedence.

Table11-1OrderofPrecedenceforOnlineRedoLogFilenameCreation

Order

Method

Result

SpecifytheLOGFILEclauseofDUPLICATEcommand.

Createsonlineredologsasspecified.

SetLOG_FILE_NAME_CONVERTinitializationparameter.

Transformstargetfilenames,forexample,fromlog_*toduplog_*.Notethatyoucanspecifymultipleconversionpairs.

Thisparameterallowstheredologtoexistaslongasthesizematches,becauseitusestheREUSEparameterwhencreatingthelogs.

Dononeoftheprecedingsteps.

Makestheduplicatefilenamesthesameasthetargetfilenames.YoumustspecifytheNOFILENAMECHECKoptionwhenusingthismethodandtheduplicatedatabaseshouldbeinadifferenthost.

TheorderofprecedencedetermineshowRMANrenamestheonlineredologs.Forexample,ifyouspecifyboththeLOGFILEclauseandtheLOG_FILE_NAME_CONVERTparameter,thenRMANusestheLOGFILEclause.Ifyouspecifyneitherofthefirsttwooptions,thenRMANusestheoriginaltargetredologfilenamesfortheduplicatedatabasefiles.

Caution:

Ifthetargetandduplicatedatabasesareinthesamehost,thendonotusethenameofanonlineredologcurrentlyinusebythetargetdatabase.

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