How to avoid ORA-21561 : OID generation failed

Today we had to create a new test database in our virtual environment ...

our sys admin has duplicated an existing one but when i started to create a database with dbca, ive got an ORA-21561 : OID generation failed

I edited the /etc/hosts file and verify that the local node is correctly identified with a mapping for both the short and fully qualified name of the host.  

How to configure Firewall rules in Red Hat for Oracle listener with iptables

One of our Oracle databases is running on RedHat Enterprise Linux 5.3. Listener is running on 1521

But I can connect to the database only from server itself. From no other machines I can connect to my database. IPTables is blocking them on 1521.

So, I’m adding a new rule to IPTables so any traffic to 1521 is allowed.

I added the rule, saved the rule and restarted the IPTables service. Saving and restarting is not required to have the rule to be active but better not to let the rule forgotten.

iptables -I INPUT -p tcp –dport 1521 -j ACCEPT

Now, it works. I can connect from other machines 

Oracle listener commands

lsnrctl help command will display all available listener commands. In Oracle 11g following are the available listener commands.

• start - Start the Oracle listener
• stop - Stop the Oracle listener
• status - Display the current status of the Oracle listener
• services - Retrieve the listener services information
• version - Display the oracle listener version information
• reload - This will reload the oracle listener SID and parameter files. This is equivalent to lsnrctl stop and lsnrctl start.
• save_config – This will save the current settings to the listener.ora file and also take a backup of the listener.ora file before overwriting it. If there are no changes, it will display the message “No changes to save for LISTENER”
• trace - Enable the tracing at the listener level. The available options are ‘trace OFF’, ‘trace USER’, ‘trace ADMIN’ or ‘trace SUPPORT’
• spawn - Spawns a new with the program with the spawn_alias mentioned in the listener.ora file
• change_password – Set the new password to the oracle listener (or) change the existing listener password.
• show - Display log files and other relevant listener information.