Host already in another Cluster

A host can only exist in one Cluster at a time.

If an "Add Existing Cluster"-job fails, and a subsequent retry throws the error:

"Host 1.2.3.4:nnnn is already in an other cluster."

Then you can do the following things in order

1. Check if you have an /etc/cmon.d/cmon_X.cnf file that contains the hostname and remove the file:

   rm /etc/cmon.d/cmon_X.cnf 

2. Delete the host from server_node, mysql_server, and hosts table.

   mysql -ucmon -p -h127.0.0.1
   use cmon;
   DELETE FROM server_node WHERE hostname='1.2.3.4';
   DELETE FROM mysql_server WHERE hostname='1.2.3.4';
   DELETE FROM hosts WHERE hostname='1.2.3.4';

3. Restart cmon:

   service cmon restart

Notes:
You may have to execute the deletion several times for each hostname/IP of the cluster you are trying to add

The '1.2.3.4' is an example address.

The X in cmon_X.cnf should be replaced by a number.

Be careful to not remove the wrong cmon_X.cnf file