In the case you do not like an Oracle RAC for redundancy it is possible to use the RDBSyncForward feature to replicate history data to a second Oracle database.

WinCC OA primarily writes the history data to the first database. Values are replicated from the first database to the second database by Oracle-Packages (part of WinCC OA). When the first database goes down then WinCC OA will continue to write history data to the second database. When the first database gets up and running again then WinCC OA will switch back to the first database and the history data which was written to the second database will be replicated from the second database to the first database.

The bi-directional replication is done asynchronously (periodically)! If one database crashes some history data may be lost.

Prepare two RDB configuration files

RDB_config_DB1.sql and RDB_config_DB2.sql.

Use RDB_config_template.sql: C:\Siemens\Automation\WinCC_OA\3.12\data\RDBSetup\ora\RDB_config_template.sql

Example configuration file with ASM is shown at the end.
The following lines are important for the data replication.

RDB_config_DB1.sql:

define whatpackage = 'fwd'
define connect_first = '&connect_identifier'
define connect_second = 'DB2'
define whatinstall = '3'
define syncjob_intval = 1


RDB_config_DB2.sql:

define whatpackage = 'fwd'
define connect_first = '&connect_identifier'
define connect_second = 'DB1'
define whatinstall = '3'
define syncjob_intval = 1


Prepare the TNSNAMES.ORA
It must contain both databases and must be deployed to the WinCC OA server(s) and to the database servers!
An TNSNAMES.ORA example you will find below.

Change to RDBSetup directory
C:\Siemens\Automation\WinCC_OA\3.12\data\RDBSetup\ora

Execute the RDB-Manager-Setup-Script for the first Oracle-Database.
> win_install.bat/unix_intall.sh _DB1

Execute the RDB-Manager-Setup-Scriptfor the second Oracle-Database.
> win_install.bat/unix_intall.sh _DB2

Change to sync subdirectory C:\Siemens\Automation\WinCC_OA\3.12\data\RDBSetup\ora\sync

Execute the sync setup for database 1
> sync_setup _DB1 ..\

Execute the sync setup for database 2
> sync_setup _DB2 ..\

Check arc_log table for (error)messages
select * from arc_log order by arc_log_id desc

Adapt WinCC OA config file
Important for the data replication is the following configuration:
[ValueArchiveRDB]
Db = "DB1,DB2"

RDB archive group configuration
In WinCC OA go to system management / database / RDB archive groups and set the check box "forwarding" for the archive groups you wanna sync.

WinCC OA config file

[general]
useRDBArchive = 1
useRDBGroups = 1

[ValueArchiveRDB]
DbUser = "RDBSYNC"
DbPass = "manager"
DbType = "ORACLE"
Db = "DB1,DB2"
writeWithBulk = 1

[ctrl]
queryRDBdirect = 1
CtrlDLL = "CtrlADO"
CtrlDLL = "CtrlRDBArchive"
CtrlDLL = "CtrlRDBCompr"

[ui]
queryRDBdirect = 1
CtrlDLL = "CtrlADO"
CtrlDLL = "CtrlRDBArchive"
CtrlDLL = "CtrlRDBCompr"


TNSNAMES.ORA

DB1 =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = Linux-DB-01)(PORT = 1521))
(CONNECT_DATA = (SERVICE_NAME = DB1))
)

DB2 =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = Linux-DB-02)(PORT = 1521))
(CONNECT_DATA = (SERVICE_NAME = DB2))
)


RDB_config_DB1.sql

define connect_identifier = 'DB1'
define sysdba_user = 'SYS'
define yesno_newuser = 'yes'
define schema_user = 'RDBSYNC'
define app_user = 'RDBSYNCAPP'
define use_rman = 'rman'
define os_sys = 'unix'
define zip_backup = 'no'
define sequence_start = 100000
define sequence_maxvalue = 199999
define path_dbfile = '+DATA/WINCCOA/RDBSYNC/'
define path_tempdbfile = '+DATA/WINCCOA/RDBSYNC/'
define path_oraclebin = '/u01/app/oracle/product/12.1.0/dbhome_1/bin/'
define instance_name = 'DB1'
define host_name = 'linux-db-01'
define path_backup = '/u01/app/oracle/fast_recovery_area/DB1/winccoa/'
define path_alert = '+DATA/WINCCOA/RDBSYNC/'
define path_event = '+DATA/WINCCOA/RDBSYNC/'
define mytimezone = 'Europe/Vienna'
define asm_instance = '+ASM'
define service_name = 'DB1'
define number_db_storage = 1

define whatpackage = 'fwd'
define connect_first = '&connect_identifier'
define connect_second = 'DB2'
define whatinstall = '3'
define syncjob_intval = 1


RDB_config_DB2.sql

define connect_identifier = 'DB2'
define sysdba_user = 'SYS'
define yesno_newuser = 'yes'
define schema_user = 'RDBSYNC'
define app_user = 'RDBSYNCAPP'
define use_rman = 'rman'
define os_sys = 'unix'
define zip_backup = 'no'
define sequence_start = 100000
define sequence_maxvalue = 199999
define path_dbfile = '+DATA/WINCCOA/RDBSYNC/'
define path_tempdbfile = '+DATA/WINCCOA/RDBSYNC/'
define path_oraclebin = '/u01/app/oracle/product/12.1.0/dbhome_1/bin/'
define instance_name = 'DB2'
define host_name = 'linux-db-02'
define path_backup = '/u01/app/oracle/fast_recovery_area/DB1/winccoa/'
define path_alert = '+DATA/WINCCOA/RDBSYNC/'
define path_event = '+DATA/WINCCOA/RDBSYNC/'
define mytimezone = 'Europe/Vienna'
define asm_instance = '+ASM'
define service_name = 'DB2'
define number_db_storage = 1

define whatpackage = 'fwd'
define connect_first = '&connect_identifier'
define connect_second = 'DB1'
define whatinstall = '3'
define syncjob_intval = 1
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