From OpenSCADAWiki
Redundancy of the data sources
Redundancy in general and of the data sources in particular serves to increase the overall level of fault-tolerance of the solution by integrating the redundant nodes in collaboration with the main node. In case of failure of the main node, the grab of the main node functions by the redundant one takes place. The redundant scheme can work in the mode of the load distribution between the co-operating nodes.