@Selene Please take a backup of database and then you can follow below steps:    Find the Cloudera Manager server's database details from file /etc/cloudera-scm-server/db.properties. Log in to CM database server. Check if there is more than one user admin in the system. Take a back up of password_hash and password_salt of the Admin user and paste them into a text editor: SELECT password_hash, password_salt FROM users WHERE user_id = 1; Update password_hash and password_salt for user "admin" using the following command: update USERS set password_hash='2518db3278f704558ece63f469af87a7c12dbad8ff0971d3b677e291d61b44fc', password_salt=-5792243850706636683 WHERE user_id = 1;  Log in to the CM interface using admin user and admin password.   ... View more

@mike_bronson7 The similar discussion happened on one of other Community thread by @Shelton You can follow this here: https://community.cloudera.com/t5/Support-Questions/add-new-data-node-to-existing-cluster/td-p/213133   Also the decommissioning is more suitable approach you can see this doc more more details though: https://docs.cloudera.com/HDPDocuments/Ambari-2.7.3.0/managing-and-monitoring-ambari/content/amb_manage_components_on_a_host.html ... View more