As per Esri, it is not recommended to use multimachine sites with ArcGIS GeoEvent Server. Instead, you should configure multiple independent sites to dedicate ArcGIS GeoEvent Server machine resources to specific real-time data streams.
http://server.arcgis.com/en/server/latest/get-started/windows/additional-server-deployment.htm#ESRI_...
We need to have a solution where we can have ArcGIS GeoEvent Server in HA mode with shared state, that receives input from a custom application server.
Please provide us with any suggestions.