There are two general modes of Server Redundancy, transparent and non-transparent.
In transparent Redundancy the Failover of Server responsibilities from one Server to another is transparent to the Client. The Client is unaware that a Failover has occurred and the Client has no control over the Failover behaviour. Furthermore, the Client does not need to perform any actions to continue to send or receive data.
In non-transparent Redundancy the Failover from one Server to another and actions to continue to send or receive data are performed by the Client. The Client must be aware of the Redundant Server Set and must perform the required actions to benefit from the Server Redundancy.
The ServerRedundancy Object defined in OPC 10000-5 indicates the mode supported by the Server. The ServerRedundancyType ObjectType and its subtypes TransparentRedundancyType and NonTransparentRedundancyType defined in OPC 10000-5 specify information for the supported Redundancy mode.