hi @DataMike , The Balancer role is normally added (by default) when the HDFS service is installed, so the "Balancer" Resides usally in your nameNode , but to make sure where it's assigned you can check HDFS->Instances  then check the role Type , you'll find the role 'balancer' assigned to a host ( usally it's the nameNode ) .   for  your second question I guess it's better to use the nameNode just to maintain the architecture since we're talking about checking all the other DataNodes,moving blocks...  ... View more

@bgooley  , thank you for your feedback and your clear explanation ,  in fact the problem was resolved by removing the contents of /var/lib/hadoop-yarn/yarn-nm-recovery/ directory and then the Nodemanager role started successfully. the solution that I've found was from   : https://community.cloudera.com/t5/Batch-Processing-and-Workflow/Yarn-NodeManager-fails-to-start-and-crashing-with-SIGBUS/m-p/66590#M3611 ... View more