1. Back up Current Data

Stop the original Ambari Server.

ambari-server stop

Create a directory to hold the database backups.

cd /tmp
mkdir dbdumps
cd dbdumps/

Create the database backups.

pg_dump -U $AMBARI-SERVER-USERNAME ambari > ambari.sql Password: $AMBARI-SERVER-PASSWORD 
pg_dump -U $MAPRED-USERNAME ambarirca > ambarirca.sql Password: $MAPRED-PASSWORD

Substitute the values you set up at installation for $AMBARI-SERVER-USERNAME, $MAPRED-USERNAME, $AMBARI-SERVER-PASSWORD, and $MAPRED-PASSWORD. Defaults are ambari-server/bigdata and mapred/mapred.