Purpose --

To overcome physical standby lag online using duplicate from active database. The standby lag is huge, “incremental from scn” backup size if huge & taking long time There is no enough disk space on the Primary/standby to accommodate the backup

Steps -

1- Check the no. of hours standby is behind primary,

2- Shut down all the standby instances and startup nomount on instance 1

3- Make sure password file has been copied to all the database nodes of standby

4- Configure tnsnames.ora in primary and standby , put the tns entries in tnsnames.ora of both Primary & standby

5- Make sure you are able to connect sqlplus with the above connect string from both primary and standby

6- No changes required in init.ora file if standby setup was already in place

7- Make sure the snapshot controlfile is configured for a shared filesystem in primary in case of RAC, else duplicate will fail with error ‘ target is likely on local filesystem‘

rman target 
    / CONFIGURE SNAPSHOT CONTROLFILE NAME TO '/sharedlocation/cntrl/snapcf_dev.f';

• Make sure there is enough free space in Archive & FRA directories of standby

On standby –

rman target sys/xxxxxx@PRIMARY auxiliary sys/xxxxx@STANDBY

run { 
CONFIGURE DEVICE TYPE DISK PARALLELISM 32; 
duplicate target database for standby from active database dorecover nofilenamecheck ;
 }

• After performing all the memory script tasks (backup, arch catalog, datafile switch, datafile copy.....), the above command will fail with below error at the end and this can be ignored.

RMAN-00571: =========================================================== RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS =============== RMAN-00571: =========================================================== RMAN-03002: failure of Duplicate Db command at 07/07/2015 13:22:38 RMAN-05501: aborting duplication of target database RMAN-03015: error occurred in stored script Memory Script RMAN-03009: failure of switch command on clone_default channel at 07/07/2015 13:22:38 ORA-19563: datafile copy header validation failed for file /u01/oradata/system_1.dbf

Monitor the recovery on standby --

SELECT PROCESS, STATUS, THREAD#, SEQUENCE#, BLOCK#, BLOCKS FROM V$MANAGED_STANDBY;

If dataguard broker is configured then you need to recreate standby control and redolog files