I have a solution to a problem which vexed me for quite some time:
Quite some time ago, I posted about PolyBase and the Hortonworks Data Platform 2.5 (and later) sandbox.
The summary of the problem is that data nodes in HDP 2.5 and later are on a Docker private network. For most cases, this works fine, but PolyBase expects publicly accessible data nodes by default—one of its performance enhancements with Hadoop was to have PolyBase scale-out group members interact directly with the Hadoop data nodes rather than having everything go through the NameNode and PolyBase control node.
Click through for the solution.