# Dataguard configuration

	DGMGRL> show configuration

	Configuration - asty

	  Protection Mode: MaxPerformance
	  Members:
	  astyprd - Primary database
	    astydrp - Physical standby database 


	DGMGRL> show database 'astydrp'

	Database - astydrp

	  Role:                PHYSICAL STANDBY
	  Intended State:      APPLY-ON
	  Transport Lag:       0 seconds (computed 1 second ago)
	  Apply Lag:           0 seconds (computed 1 second ago)
	  Average Apply Rate:  803.00 KByte/s
	  Real Time Query:     OFF
	  Instance(s):
	    ASTYDRP

# Simulate a gap

Stop the standby database. 

On primary, switch 3-4 times the archivelog on primary and delete all archived logs:

	SQL> alter system archive log current;
	RMAN> delete noprompt force archivelog all;

To complicate the situation, add 2 new datafile and create a new tablespace on primary.

	SQL> alter tablespace SYSTEM add datafile size 10M autoextend OFF;
	SQL> alter tablespace SYSAUX add datafile size 10M autoextend OFF;
	SQL> create tablespace NAL_HUTTA datafile size 10M autoextend ON next 10M;

Repeat switch/delete archivelog operation on primary:

	SQL> alter system archive log current;
	RMAN> delete noprompt force archivelog all;

Start the standby database in **MOUNT** mode, let it trying to resolve the gap and check the status of the syncronisation.  
On primary:

	alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';
	set lines 200

	select THREAD#, max(SEQUENCE#), max(FIRST_TIME),max(NEXT_TIME),max(COMPLETION_TIME) 
	from gv$archived_log group by THREAD#;

On standby:

	alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss';
	set lines 200

	select THREAD#, max(SEQUENCE#), max(FIRST_TIME),max(NEXT_TIME),max(COMPLETION_TIME) 
	from gv$archived_log
	where APPLIED='YES' group by THREAD#;


# Syncronize the standby

Cancel **MRP** on standby:

	DGMGRL> edit database 'astydrp' set STATE='LOG-APPLY-OFF';

Try to recover the standby and note down the required `SCN`:

	SQL> recover standby database;

Normaly it should be the same as:

	SQL> select 1+CURRENT_SCN from v$database;

On primary, identify all datafiles created after this `SCN`; in my example `SCN=5681090`

	SQL> select FILE#,NAME from v$datafile where CREATION_CHANGE# >= 5681090;

Backup datafiles and generate a new standby controlfile:

	run{
	  set nocfau;
	  allocate channel ch01 device type disk format '/mnt/yavin4/tmp/_oracle_/orabackup/temp/%d_%U_%s_%t.bck';
	  allocate channel ch02 device type disk format '/mnt/yavin4/tmp/_oracle_/orabackup/temp/%d_%U_%s_%t.bck';
	  allocate channel ch03 device type disk format '/mnt/yavin4/tmp/_oracle_/orabackup/temp/%d_%U_%s_%t.bck';
	  allocate channel ch04 device type disk format '/mnt/yavin4/tmp/_oracle_/orabackup/temp/%d_%U_%s_%t.bck';
	  backup as compressed backupset datafile 17,18,19;
	  release channel ch01;
	  release channel ch02;
	  release channel ch03;
	  release channel ch04;
	  allocate channel ch01 device type disk format '/mnt/yavin4/tmp/_oracle_/orabackup/temp/%d_%U_%s_%t.ctl';
	  backup current controlfile;
	  release channel ch01;
	}


Restart the standby in mode **NOMOUNT** and restore the standby controfile:

	RMAN> restore standby controlfile from '/mnt/yavin4/tmp/_oracle_/orabackup/temp/ASTY_0l1678fs_21_1_1_21_1113825788.ctl';

Alternatively, you can restore the standby controfile from active database:

	RMAN> restore standby controlfile from service ASTYPRD_DGMGRL;

Mount the standby database:

	RMAN> alter database mount;

Restore and new datafiles:

	RMAN> restore datafile 17,18,19;

Catalog recovery area and old standby datafiles:

	RMAN> catalog start with '/data/ASTYDRP' noprompt;
	RMAN> catalog start with '/fra/ASTYDRP' noprompt;

At this moment, because of fresh restored controlfile, Oracle see the datafiles as datafile copy:

	RMAN> list datafilecopy all;

Switch database to copy:

	RMAN> switch database to copy;


To recover standby using *from SCN* backupset, we can proceed from active database or using physical backupset:

	rman auxiliary /
	run {
	  allocate channel pri1 device type DISK;
	  allocate channel pri2 device type DISK;
	  allocate channel pri3 device type DISK;
	  allocate channel pri4 device type DISK;
	  recover database from service ASTYPRD_DGMGRL using compressed backupset section size 8G;
	}

Clear standby redolog:

	SQL> select 'ALTER DATABASE CLEAR LOGFILE GROUP '||GROUP#||';' from v$standby_log;

Enable **MRP**:

	DGMGRL> edit database 'astydrp' set STATE='ONLINE';