Create Data Guard's standby database

After the primary database has been prepared for Data Guard, it's ready to be duplicated to the standby site. The following guide uses active duplication to create a consistent copy of the database.

As a reminder, the following examples are used throughout this guide:

Database unique name	Server hostnames	RAC instance names	Role
`DBDG_SITE1`	`site1db1`, `site1db2`	`DBDG_SITE11`, `DBDG_SITE12`	Primary
`DBDG_SITE2`	`site2db1`, `site2db2`	`DBDG_SITE21`, `DBDG_SITE22`	Standby

The Bare Metal Solution servers running Oracle in this guide are configured with the following environment variables:

Environment variable name	Value
`ORACLE_BASE`	`/apps/oracle/oracle_base`
`ORACLE_HOME`	`/apps/oracle/19.0.0/db_home1`

You might need to modify the environment variable paths depending on your setup.

Set up the standby database

Configure the database connectivity

Log in to each Bare Metal Solution server in the standby location and modify the $ORACLE_HOME/network/admin/tsnames.ora file to update the net service configuration:

DBDG_SITE2 =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = DBDG_SITE2_SCAN_HOSTNAME)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = DBDG_SITE2) (UR=A)
   )
 )

DBDG_SITE1 =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = DBDG_SITE1_SCAN_HOSTNAME)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = DBDG_SITE1)
    )
  )

Configure a temporary listener

To avoid restarting the listener used for other database connections, database duplication is performed using a temporary listener. This example uses port 1523, but you can use any port that is open for communication between the clusters. You delete this temporary listener after database duplication.

Log in to the first Bare Metal Solution server in the standby location to be used during the database duplication process. Modify the $ORACLE_HOME/network/admin/listener.ora file to update the net service configuration:

LISTENER_DBDG_SITE2 =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = site1db1)(PORT = 1523))
    )
  )

SID_LIST_LISTENER_DBDG_SITE2 =
  (SID_LIST =
    (SID_DESC =
      (GLOBAL_DBNAME = DBDG_SITE2_DGMGRL)
      (ORACLE_HOME = ORACLE_HOME)
      (SID_NAME = DBDG_SITE21)
    )
  )
ADR_BASE_LISTENER = /apps/oracle/oracle_base

Start the temporary listener:
```
lsnrctl start LISTENER_DBDG_SITE2
```

Prepare the standby database

Each database instance requires a directory to store audit logs. Create the audit file directory on each Bare Metal Solution server in the standby database location:
```
mkdir -p /apps/oracle/oracle_base/admin/DBDG_SITE2/adump
```
Modify the $ORACLE_HOME/dbs/initDBDG_SITE21.ora file that was copied to the standby database server earlier:
1. Set the db_unique_name to the new standby database name.
2. Modify any instance-specific parameters to reflect the instance names for the standby database. Some examples are:
  - instance_number
  - thread
  - undo_tablespace
3. Set the audit_file_dest parameter to use the directory created in the previous step.
4. If the ASM diskgroups in each location use different names, modify the db_file_name_convert and log_file_name_convert parameters to match the new file locations.
5. Comment out the control_files parameter.
The following example shows an updated database parameter file with modifications using the examples provided in this guide. Note that your parameter file will contain additional parameters that are specific to your database setup. Only the parameters that require modification for the standby are shown:
```
*.db_unique_name='DBDG_SITE2'
DBDG_SITE21.instance_number=1
DBDG_SITE22.instance_number=2
DBDG_SITE21.thread=1
DBDG_SITE22.thread=2
DBDG_SITE21.undo_tablespace='UNDOTBS1'
DBDG_SITE22.undo_tablespace='UNDOTBS2'
*.audit_file_dest='/apps/oracle/oracle_base/admin/DBDG_SITE2/adump'
#*.control_files='+DATA/DBDG_SITE1/CONTROLFILE/current.258.1091317089','+RECO/DBDG_SITE1/CONTROLFILE/current.257.1091317089'
```
In the /etc/oratab file, add an entry so the oraenv command can set environment variables for the standby database:
```
DBDG_SITE21:ORACLE_HOME:N
```

Create the standby database

Set the ORACLE_SID environment variable so you can connect to the standby database:
```
source oraenv <<< "DBDG_SITE21"
```
You should receive the response The Oracle base has been set to /apps/oracle/oracle_base.
Before duplicating the primary database, you must manually start the standby instance on one node. Log in to the first Bare Metal Solution server in the standby location, start SQL*Plus, then startup the standby database in nomount mode by using the pfile:
```
sqlplus / as sysdba
```
```
STARTUP NOMOUNT PFILE='/apps/oracle/19.0.0/db_home1/dbs/initDBDG_SITE21.ora';
```
If successful, you should receive a response similar to the following example:
```
ORACLE instance started.
Total System Global Area 1.2885E+10 bytes
Fixed Size 15988824 bytes
Variable Size 1845493760 bytes
Database Buffers 1.1006E+10 bytes
Redo Buffers 17563648 bytes
```
Exit SQL*Plus after starting the instance:
```
EXIT;
```
Verify connectivity to the standby database service. From each Bare Metal Solution server in the primary database location, attempt to connect to the standby instance by using SQL*Plus. Enter the SYS remote login password manually to successfully connect to the instance.
```
sqlplus sys@DBDG_SITE2_FOR_DUPLICATION as sysdba
```
If successful, you should receive a standard SQL*Plus prompt, where you can check the instance parameters:
```
SHOW PARAMETER DB_UNIQUE_NAME;
```
You should receive a response similar to the following:
```
                NAME        TYPE                          VALUE
    ---------------- ----------- ------------------------------
      db_unique_name      string      DBDG_SITE2
```
Exit SQL*Plus after checking the DB_UNIQUE_NAME parameter:
```
EXIT;
```
Connect to Recovery Manager, then run the duplicate command to duplicate the standby from the active primary database:
```
rman TARGET sys@DBDG_SITE1 AUXILIARY sys@DBDG_SITE2_FOR_DUPLICATION
```
```
DUPLICATE TARGET DATABASE FOR STANDBY FROM ACTIVE DATABASE NOFILENAMECHECK;
```
If successful, after processing you should receive a message similar to the following example:
```
Finished Duplicate Db at ...
```
Exit Recovery Manager:
```
EXIT;
```

Finalize the standby database creation

During database duplication, ASM creates new control files for the standby database. Connect to the new standby instance and get the new control file name(s). The following example shows two control files stored in the +DATA and +RECO diskgroups:

sqlplus / as sysdba

SET LINESIZE 140
COLUMN NAME FORMAT a15
COLUMN VALUE FORMAT a125
SELECT NAME, VALUE FROM V$PARAMETER WHERE NAME='control_files';

The control file name(s) are shown in the "Value" field:

           NAME     VALUE
--------------- ----------------------------------------------------------------------------------------------------
  control_files   +DATA/DBDG_SITE2/CONTROLFILE/current.258.1091317089, +RECO/DBDG_SITE2/CONTROLFILE/current.257.1091317089

Record the control file names from the previous step, and replace any entries for the control_files parameter in $ORACLE_HOME/dbs/initDBDG_SITE21.ora with the new values. If there are multiple control files, encapsulate each in single quotes, separated by a comma:
```
*.control_files='+DATA/DBDG_SITE2/CONTROLFILE/current.258.1091317089','+RECO/DBDG_SITE2/CONTROLFILE/current.257.1091317089'
```

Connect to the standby database with SQL*Plus and create a new spfile from the modified pfile:

sqlplus / as sysdba

CREATE SPFILE='+DATA/DBDG_SITE2/spfileDBDG_SITE2' FROM PFILE='/apps/oracle/19.0.0/db_home1/dbs/initDBDG_SITE21.ora';

Copy the password file to the ASM diskgroup by using the asmcmd command:

asmcmd cp /apps/oracle/19.0.0/db_home1/dbs/orapwDBDG_SITE21.ora +DATA/DBDG_SITE2/orapwDBDG_SITE2

Shut down the standby database instance and delete the temporary pfile and password file:

sqplus / as sysdba

SHUTDOWN IMMEDIATE;
EXIT;

rm $ORACLE_HOME/dbs/orapwDBDG_SITE21.ora $ORACLE_HOME/dbs/initDBDG_SITE2.ora

Stop the temporary listener used for database duplication on the first Bare Metal Solution server in the standby database location:
```
lsnrctl stop LISTENER_DBDG_SITE2
```
Remove the temporary entries in the $ORACLE_HOME/network/admin/listener.ora file on the first Bare Metal Solution server in the standby database location.

Add the new standby database and instances to the cluster registry by using the srvctl command:

srvctl add database \
  -db DBDG_SITE2 \
  -oraclehome /apps/oracle/19.0.0/db_home1 \
  -spfile +DATA/DBDG_SITE2/spfileDBDG_SITE2 \
  -pwfile +DATA/DBDG_SITE2/orapwDBDG_SITE2 \
  -role PHYSICAL_STANDBY \
  -startoption MOUNT

srvctl add instance \
  -db DBDG_SITE2 \
  -instance DBDG_SITE21 \
  -node site2db1

srvctl add instance \
  -db DBDG_SITE2 \
  -instance DBDG_SITE22 \
  -node site2db2

Start the standby database by using the srvctl command:
```
srvctl start database -db DBDG_SITE2
```

Next steps

Next, configure and enable the Data Guard broker.