We have HDP cluster with 152 workers machines - `worker1.duplex.com` .. `worker152.duplex.com` , While all machines are installed on RHEL 7.9 version
We are trying to delete the last host - `worker152.duplex.com` from Ambari server or actually from PostgreSQL DB as the following
First we need to find the `host_id`
select host_id from hosts where host_name='worker152.duplex.com';
and host_id is:
host_id
---------
51
(1 row)
Now we are deletion this `host_id` - 51
delete from execution_command where task_id in (select task_id from host_role_command where host_id in (51));
delete from host_version where host_id in (51);
delete from host_role_command where host_id in (51);
delete from serviceconfighosts where host_id in (51);
delete from hoststate where host_id in (51);
delete from kerberos_principal_host WHERE host_id='worker152.duplex.com';
delete from hosts where host_name in ('worker152.duplex.com');
delete from alert_current where history_id in ( select alert_id from alert_history where host_name in ('worker152.duplex.com'));
Now we verify that `host_id` - 51 that represented the host - `worker152.duplex.com` isn't exists By the following verification
ambari=> select host_name, public_host_name from hosts;
host_name | public_host_name
--------------------------+--------------------------
worker1.duplex.com
.
.
.
worker151.duplex.com
As we can see above the host `worker151.duplex.com` not exist and that's fine , and indeed seems That host - `worker151.duplex.com` was deleted from PostgreSQL DB
Now we restarting the `Ambari-server` in order to take affect ( its also restart the PostgreSQL service )
ambari-server restart
Using python /usr/bin/python
Restarting ambari-server
Waiting for server stop...
Ambari Server stopped
Ambari Server running with administrator privileges.
Organizing resource files at /var/lib/ambari-server/resources...
Ambari database consistency check started...
Server PID at: /var/run/ambari-server/ambari-server.pid
Server out at: /var/log/ambari-server/ambari-server.out
Server log at: /var/log/ambari-server/ambari-server.log
Waiting for server start.........................
Server started listening on 8080
DB configs consistency check: no errors and warnings were found.
After Ambari server started , we are surprised because the `host_id` - 51 or host - `worker152.duplex.com` , is still exist as the following
ambari=> select host_name, public_host_name from hosts;
host_name | public_host_name
--------------------------+--------------------------
worker1.duplex.com
.
.
.
worker152.duplex.com
We not understand why this host back again in spite we delete this record
We also tried to delete historical data by the following but this isn't help
ambari-server db-purge-history --cluster-name hadoop7 --from-date 2024-01-01
Using python /usr/bin/python
Purge database history...
Ambari Server configured for Embedded Postgres. Confirm you have made a backup of the Ambari Server database [y/n]yes
ERROR: The database purge historical data cannot proceed while Ambari Server is running. Please shut down Ambari first.
Ambari Server 'db-purge-history' completed successfully.
1. Why host returned after `Ambari-server` restart ?
2. what is wrong with out deletion process?
PostgreSQL Version:
postgres=# SHOW server_version;
server_version
----------------
9.2.24
(1 row)
links:
https://www.andruffsolutions.com/removing-old-host-data-from-ambari-server-and-tuning-the-database/
https://community.cloudera.com/t5/Support-Questions/how-to-remove-old-registered-hosts-from-DB/m-p/2...
Michael-Bronson
