Listener status check

Job details

Name:	Listener status check
Platform:	Oracle
Category:	Availability
Description:	Checks listener status to verify if up and running, requires java support in the database.
Long description:	Task checks listener status to verify that listener is up and running. This task requires java support in the database.
Version:	3.2
Default schedule:	0,5,10,15,20,25,30,35,40,45,50,55 * * *
Requires engine install:	Yes
Compatibility tag:	.[type=‘instance’ & databasetype=‘oracle’]/.[hasengine=‘YES’ & eleven_and_above = ‘1′ & enable_java = ‘1′]

Parameters

Name	Default value	Description
Delete statistics older than (hours)	336
Listener status string	AUTO	Give the alert the lsnrctl status exec command if it can not find it by itself. Possible values are “AUTO“ or an exec string such as “/u01/app/oracle/10.0/db_1/bin/lsnrctl status”.
Status match text	READY	This is the value to look for in the lsnrctl status line for this instance. Possible values includes, but are not limited to READY and UNKNOWN.
Named listener name		Put a value here, if you want to check a named listener

Job Summary

Purpose: The purpose of this job is to monitor the status of Oracle listeners to ensure they are operational and ready, with specific supports for databases with Java enabled and version 11 or higher.
Why: This job is important because ensuring the availability of Oracle database listeners is crucial for database connectivity and performance. If these listeners are down or not responsive, it can affect database operations and result in downtimes or performance degradation.
Manual checking: You can check the status of the listener manually in the Oracle database using this command:

lsnrctl status

Technical Details
h3. Scheduled Check Patterns

Frequency	Description
Every 5 minutes	Checks if the listener is up and running by checking specific text (e.g., “READY“) in the output of the listener’s status command.

Dependencies

The task has a dependency on itself to ensure it can run repeatedly without conflicts.
It also relies on several database objects, such as DBW_LISTENER_CHECK_LINE, which stores the command outputs.

Cleanup Procedures

The job includes a cleanup task on failure, ensuring that if the job fails, it leaves no erroneous data that could affect subsequent checks.
Also, old statistics more than a specified number of hours old are purged to prevent data overflow and maintain database performance.

Reporting and Monitoring

Alert Conditions

If the condition for verifying the listener status fails (e.g., the listener status does not match “READY“ or the specified statuses), an alert is generated with necessary information such as execution count and any exception messages should the listener status check procedure face execution issues.

Listener Status Report

Description: Provides detailed results from the last listener status check.
Frequency: Generated every hour.
Content: Shows output lines fetched from the database regarding the last listener status, helping administrators quickly assess the current state.

Special Procedures

Java procedures and implementations are used for fetching and processing listener status from the OS level if the default SQL procedure is inadequate.
These procedures are capable of handling both Linux and Windows platforms by adjusting the commands based on the operating system type detected.

Conclusion

This job represents a critical monitoring function in database operations for Oracle instances. It ensures that listeners are functioning correctly, otherwise alerts the administrator to take appropriate action, thereby maintaining connectivity and database service levels.