Hi Bro...see the requirement of Hadoop .... what you want to be in hadoop .. admin or dev... admin part is easy as you have knowledge of Linux and hadoop is open source and working on Linux... like windows it has its own file system like HDFS.... I know hadoop admin part that is pretty easy... but if you want to be dev then you must have a programming ability. with hadoop lots of similar third party tool used in it... Java is good if you want to for dev... that give you a basic to understand all ...

Good luck....if you want to any other technology you can msg me...