@Daniel Müller This happens if you have changed the hostname of your cluster nodes after the ambari cluster installation. In thsi case because initially suppose the hostname was "hdp-3.novalocal" for the host so after starting the agent on that host it will be registered in the ambri DB with name "hdp-3.novalocal", But after few days if you will change the agent hostname to "hdp-3" then a new host will eb registered to the ambari cluster (even thoug the host is same but the hostname was different earlier) The stop the Ambari Server # ambari-server stop Please take ambari DB Dump. # pg_dump -U ambari ambari > /tml/ambari_bkp.sql . We cleaned unwanted hosts from DB and delete those selected hosts. Get their "host_id" of those hosts which you want to clean. Connect to ambari DB. # psql -U ambari ambari Password: bigdata Queries: To find the host_id; select host_id from hosts where host_name='hdp-1.novalocal'; select host_id from hosts where host_name='hdp-2.novalocal'; select host_id from hosts where host_name='hdp-3.novalocal'; . Using the above command we will get the "host_id". As we know that the above hosts need to be deleted, So delete them as following. Suppose the host_id is respectively 111,222,333 delete from execution_command where task_id in (select task_id from host_role_command where host_id in (111,222,333)); delete from host_version where host_id in (111,222,333); delete from host_role_command where host_id in (111,222,333); delete from serviceconfighosts where host_id in (111,222,333); delete from hoststate where host_id in (111,222,333); delete from hosts where host_name in ('hdp-1.novalocal'); delete from hosts where host_name in ('hdp-2.novalocal'); delete from hosts where host_name in ('hdp-3.novalocal'); delete from alert_current where history_id in ( select alert_id from alert_history where host_name in ('hdp-1.novalocal')); delete from alert_current where history_id in ( select alert_id from alert_history where host_name in ('hdp-2.novalocal')); delete from alert_current where history_id in ( select alert_id from alert_history where host_name in ('hdp-3.novalocal')); The restart Ambari Server # ambari-server start . NOTE: Regarding the changing hostname issue I have written an article some time back, You should refer to the following article which explains why does it happen in Cloud environment and how to fix it. https://community.hortonworks.com/articles/42872/why-ambari-host-might-have-different-public-host-n.html . ... View more

@Robin Dong Looks like one of your host is causing the problem. Please check the following: 1). Check the "host_version" table and findout which host is not pointing to "2.5.3.0-37" SELECT * FROM host_version; 2). Login to the problematic host using SSH and then run the following command to find out if it really has the 2.5.3.0-37 packages installed or not? # hdp-select 3). If you see that the hdp-select command output shows that all the packages installed to that host is having the correct version then following the next step. 4). If you find the problematic host then find it's host_id from the "hosts" table and then check if it is pointing to OLD repo_version_id , if yes then update it to point to the current version. UPDATE host_version SET state='CURRENT' WHERE host_id='xx'; . Also you can update the "repo_version_id" for this host to point to the latest version of repo (if it is not set already) Please make sure that after this change the host is pointing to the repo_version_id mentioned in the "cluster_version" table which has state as "CURRENT". . 5). After the DB changes (commits) ambari-server need to be restarted. # ambari-server restart . ... View more