If you have multiple Oracle WebLogic Server 12c domains on a single machine, can each domain have its dedicated Node Manager? Can a single Node Manager manage all the domains in this machine? Yes and yes.

Multiple Node Managers on a Single Machine

If you have multiple domains on your machine, say soa_dev_domain and soa_tst_domain, each domain has its own set of Node Manager configuration and startup files under $DOMAIN_HOME/nodemanager.

On the soa_dev_domain, you will find a nodemanager.domains configuration file:

oracle@soahost:/u01> cat /u01/domains/soa_dev_domain/nodemanager/nodemanager.domains

Similarly on the soa_tst_domain, the nodemanager.domains file will also exist:

oracle@soahost:/u01> cat /u01/domains/soa_tst_domain/nodemanager/nodemanager.domains

Before you start up the 2 Node Managers, make sure that each of them has a different ListenPort:

oracle@soahost:/u01> cat /u01/domains/soa_dev_domain/nodemanager/nodemanager.properties | grep Port

oracle@soahost:/u01> cat /u01/domains/soa_tst_domain/nodemanager/nodemanager.properties | grep Port

Under the Machine configuration for each domain, update the Listen Address and Listen Port in the WebLogic Admin Console accordingly:

Now you can start up both NodeManagers:

oracle@soahost:/u01> export DOMAIN_HOME_DEV=/u01/domains/soa_dev_domain
oracle@soahost:/u01> nohup $DOMAIN_HOME_DEV/bin/startNodeManager.sh >> $DOMAIN_HOME_DEV/bin/nodemanager.out &

oracle@soahost:/u01> export DOMAIN_HOME_TST=/u01/domains/soa_tst_domain
oracle@soahost:/u01> nohup $DOMAIN_HOME_TST/bin/startNodeManager.sh >> $DOMAIN_HOME_TST/bin/nodemanager.out &

Monitoring Multiple Domains with a Single Node Manager

If you wanted the Node Manager instance under the soa_dev_domain to manage multiple domains, simply add the domains to nodemanager.domains as shown:

oracle@soahost:/u01> cat /u01//domains/soa_dev_domain/nodemanager/nodemanager.domains

Now, update the machine configuration in the WebLogic Admin Console and startup Node Manager and you're good to go!