Prepare the Ambari server host for NameNode rollback

To prepare for the NameNode rollback task:

1. Log in to the Ambari server host.
2. Set the following environment variables:

   export AMBARI_USER=AMBARI_USERNAME

   Substitute the value of the administrative user for Ambari Web. The default value is admin.

   export AMBARI_PW=AMBARI_PASSWORD

   Substitute the value of the administrative password for Ambari Web. The default value is admin.

   export AMBARI_PORT=AMBARI_PORT

   Substitute the Ambari Web port. The default value is 8080.

   export AMBARI_PROTO=AMBARI_PROTOCOL

   Substitute the value of the protocol for connecting to Ambari Web. Options are http or https. The default value is http.

   export CLUSTER_NAME=CLUSTER_NAME

   Substitute the name of your cluster, which you set during installation: for example, mycluster.

   export NAMENODE_HOSTNAME=NN_HOSTNAME

   Substitute the FQDN of the host for the non-HA NameNode: for example, nn01.mycompany.com.

   export ADDITIONAL_NAMENODE_HOSTNAME=ANN_HOSTNAME

   Substitute the FQDN of the host for the additional NameNode in your HA setup.

   export SECONDARY_NAMENODE_HOSTNAME=SNN_HOSTNAME

   Substitute the FQDN of the host for the standby NameNode for the non-HA setup.

   export JOURNALNODE1_HOSTNAME=JOUR1_HOSTNAME

   Substitute the FQDN of the host for the first Journal Node.

   export JOURNALNODE2_HOSTNAME=JOUR2_HOSTNAME

   Substitute the FQDN of the host for the second Journal Node.

   export JOURNALNODE3_HOSTNAME=JOUR3_HOSTNAME

   Substitute the FQDN of the host for the third Journal Node.

3. Double check that these environment variables are set correctly.