Hadoop datanode

[sandyHadoop]

Hello everyone,
I have installed hadoop multi node cluster and hbase in 2 systems. I have used one as master and other as slave . When i start-all.sh hadoop in master machine , master machine is working properly ,but the Datanode in not starting in slave machine, instead of that Tasktracker is starting in slave .

So could you please tell me how to start Datanode instead of task tracker in slave machine?

Thanks in advance.