I am looking to develop a platform for providing user oriented reports and a analytics platform for a set of systems which collect data. There are three possible systems feeding in the data in their own RDBMS. Can someone please advise if I should go for a BI analytics tool directly or first look into integrating the data in a data warehouse or go for a Hadoop kind of data storage system. The data size presently is not enormous but would grow eventually to hundreds of TB's in 2 years. What is the starting point for this technology selection?