Easy/Different steps build lower environment or build your DR setup

PROD database to Lower environment (PROD -> DEV/TEST/UAT) 

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With PROD backup (RMAN-backups):

Option 1: Restore recover from backup 

- restore 

- recover 

- open database with reset logs 

Option 2: RMAN clone / RMAN duplicate from backup 

- duplicate target database to TESTDB backup location '/u01/backup' nofilenamecheck;

Without PROD backup (without RMAN-backups):

Option 3: RMAN active database duplicate 

$rman target sys/password@PROD 

RMAN> connect auxiliary sys/password@TESTDB

RMAN> duplicate target database to TESTDB from active database;

PROD database to DR environment (PROD -> DR) 

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With PROD backup (RMAN-backup):

Option 1: Restore recover from backup 

- restore 

- recover 

- start MRP 

Option 2: RMAN clone / RMAN duplicate from backup 

- duplicate target database for standby database backup location '/u01/backup' filenamecheck/nofilenamecheck;

- start MRP 

Without PROD backup (without RMAN-backup):

Option 3: RMAN active database duplicate 

$rman target sys/password@PROD 

RMAN> connect auxiliary sys/password@DR

RMAN> duplicate target database for standby database from active database;

- start MRP 

https://mallik034.blogspot.com/2021/05/19c-dataguard-build-document.html

Option 4: Service based standby build (from 12c onwards) (Without PROD backup)

rman target / (on Standby Side) 

RMAN> restore standby controlfile from PROD service;

RMAN> restore standby database from PROD service;

RMAN> recover standby database from PROD service;