Redundant Scenario

Note: InfluxDB® serves as an example for the scenarios in this chapter. Aside from the redundancy, all databases work the same. The various redundancy scenarios can be found in this chapter.
The following scenario is included in the basic WinCC OA - No extra package is required.

The basic integrated NGA features (locally installed InfluxDB® as shipped with WinCC OA ) as well as basic NGA features in redundant systems are included.

Figure 1. NGA deployment – redundant scenario - InfluxDB®

This is the default redundant scenario. It uses two local replicas of the InfluxDB®. The synchronization within the replicas is handled by the NGA. When the backend is on the same machine as the NGA Archiver Manager, the execution type can be either In-Proc or Out-Of-Proc, i.e. it can run as a plug-in or as a separate process.

Note: For this type of deployment the backend must use the profile InfluxDB - see chapter Name.
Figure 2. NGA deployment - redundant scenario - InfluxDB® - Single centralized database

Another scenario that you might prefer is to have a single centralized database. For this scenario at least the NGA Standard package or NGA Premium package is required. In this case redundancy is not available on the database. Having the backends local to the database server relieves the load of the WinCC OA servers. Since the backends run on a remote machine, the execution type must be Out-Of-Proc.

Note: For this type of deployment the backend must use the profile InfluxDB_nonRedundant - see chapter Name.

With the free version of InfluxDB® this scenario does not provide redundancy at database level (InfluxDB_nonRedundant).

Figure 3. NGA deployment - redundant scenario - PostgreSQL®

For redundancy with PostgreSQL® a redundant cluster can be used. For this scenario at least the NGA Standard package or NGA Premium package is required. The synchronization between the replicas is handeled by PostgreSQL®.

When the backend is on the same machine as the NGA Archiver Manager, the execution type can be either In-Proc or Out-Of-Proc, i.e. it can run as a plug-in or as a separate process.

Figure 4. NGA deployment - redundant scenario - MS SQL®

For this scenario at least the NGA Standard package or NGA Premium package is required.

When the backend is on the same machine as the NGA Archiver Manager, the execution type can be either In-Proc or Out-Of-Proc, i.e. it can run as a plug-in or as a separate process.

The redundancy for MS SQL® is implemented by the Windows Server Failover Cluster. For Windows Server Failover Cluster see the MSSQL_Redu.pdf in C:\Siemens\Automation\WinCC_OA\3.18\\data\NGA\MSSQLServer.

For details, see chapter NGA Redundancy.