I'm using giraph-1.3 built with yarn profile. For starting I configured 1 namenode and 2 datanodes on a ec2 cluster.
My application properly works because I see expected output in logs (and in output directory). I launched giraph with "-w 2" argument because I have two datanodes.

In userlogs of datanode1 I found log of first worker.  

in userlogs of datanode2 I found log of second worker and log of master too.

I expected to find log of master in the namenode i.e. I expected that master runs on namenode. Is it right?

Maybe I have to configure another datanode and then I will find master logs on this new datanode?