How to Implement AVEVA historian redundant servers on top of a redundant plant SCADA server architecture with one control client,

A single connection is active. The connector leverages the built-in trend, string variable and alarms and event redundancy of Plant Scada. Plant Scada currently does not support dual threads, one each for the historians and its partner.

The historians in a redundant setup are not intended to be a synchronized pair, where both the historian configuration and data are fully and automatically synchronized. It is up to you to make sure that the two historians are symmetrical and synchronized.

In case of Application server, it can be configured to automatically send data to both the primary historian and the specified partner. If one of the historians goes offline, the AppEngine stores the historized data until the historian comes back online. After the connection is restored, the AppEngine forwards the data to the historian that was offline. The Historian

Client automatically detects and selects the online Historian from the redundant pair.

Aveva Historian Standard - unlimited under flex license includes redundancy. 

Hi Karim Mowafy ,

The AVEVA Historian Plant SCADA Connector (V3.1) supports a redundant connection to Plant SCADA (Primary and Backup) and only a single connection to Historian. Any temporary disruption between the Connector and Historian (recommended to be located on SCADA network) will be handled by the store and forward mechanism.

To answer your first question, it is possible to setup a second Connector that points to a second Historian (redundant), which has its own store and forward mechanism and data stream. Please consult the System Platform documentation on how to setup a redundant Historian. The Connector doesn't support redundancy at the Historian connection level. So there would be two independent Connectors forwarding data to two Historians.

There isn't any special scripting required within Plant SCADA to achieve redundancy. It should work out of the box with a standard configuration. The CtAPI interface that the Connector makes use of has a layer of abstraction to ensure you get the data you need from the appropriate data source.

In terms of license requirements for Historian redundancy setup, I think it is best to contact AVEVA sales to discuss this further.