Hi @David Clissold Fixed, at: https://docs.hortonworks.com/HDPDocuments/Ambari-2.6.0.0/bk_ambari-installation-ppc/content/select_version.html ... View more

It appears we've discovered the issue. The server has a large number of cores, 160. We have edited /etc/ambari-server/conf/ambari.properties with: agent.threadpool.size.max=128 client.threadpool.size.max=128 (Just increasing to largest ^2 closer to 160); restarting the ambari-server, it appears the clients now register successfully. We should now be able to proceed with the installation. ... View more