What should I do if Oracle cannot start monitoring?

Oracle is a very popular database management system, but you may encounter some errors during use, such as Oracle being unable to start monitoring. This situation often happens, but it brings great trouble to the use of the database. This article will tell you more about the possible causes and solutions to this problem.

1. Background of the problem

When using the Oracle database management system, one of the main components you need is the listener. It is a component of the database engine that handles communication between client applications and the database, as well as routing requests between them to the correct database server. Therefore, when Oracle cannot start the listener, it may cause the service to stop and the client to be unable to connect to the database.

2. Possible reasons

1. The listener port is occupied

If there are other applications using the same port number on your machine, Oracle cannot start. listener. This usually results in a "TNS-12542" or "TNS-00512" error.

2. Listener configuration error

If the listener configuration file contains errors or is accidentally changed, Oracle may not be able to start. You can check the listener configuration file for syntax errors or to determine if the correct IP address or hostname is set.

3. Firewall or network issues

If your operating system or network configuration blocks communication between the client and server, then Oracle cannot start the listener. Check the network connection to make sure there are no firewalls blocking the connection on the required port.

4. The listener itself is infected or crashes

If your computer is infected with malware, the listener itself may have been compromised. Additionally, if the configuration file is corrupted and the listener cannot be started, you may need to start over with a backup configuration file.

3. Solution

1. Check whether the listener port is occupied

Use the following command to check the status of the port number (please replace the port number with the one you are using Port number):

lsof -i:port number

If you see a printed process, the port has been used, and you need to restart Oracle monitoring after the process is stopped. device.

2. Check the listener configuration

Before restarting the listener, first try to check whether there are errors in the listener configuration file. The default location of the Oracle listener configuration file is: $ORACLE_HOME/network/admin/listener.ora. You can use an editor such as "vi" or "nano" to open and inspect this file, if you are not sure how to inspect, please refer to the Oracle documentation for details.

3. Check the network connection

Make sure your server can be accessed. You can use the following command to test the network connection:

ping [IP address or host name]

If you cannot connect, please make sure there is no firewall blocking the connection, and make sure the server and client are on the same network.

4. Restart the listener

If no errors are found, you can try to restart the Oracle listener using the following command:

lsnrctl stop
lsnrctl start

If this still does not solve the problem, you can try restarting the server or contact Oracle technical support directly.

Oracle's inability to start the listener may be a common problem, but these solutions can help you solve the problem of damage, occupied ports, or incorrect settings. If the problem cannot be solved for a long time, please consider contacting Oracle technical support for more comprehensive help. We hope this article is helpful to you and keep your Oracle database working for you.

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