Thank you very much. But something still not clear, which is how I setup the third Namenode in Ambari 2.7. I already update hdfs-site.xml with a nn3 config, and restart HDFS which functionally normal without the third Namenode. If we should create the the third Namenode by Ambari API, as I found no place or button in Ambari GUI. ... View more

Thank you for your reply. More than one standby NameNode means we can tolerant more than two namenode failure. As we have only two namenode in Hadoop 2.x, the cluster will go down once the active and standby namenode went down. And we can have one Active NameNode and 2 or 4 Standby NameNode in Hadoop3 which can provide a better high availability. So I'am asking if Ambari could support this feature. ... View more