Starting and Stopping Connection Manager

In Oracle 12c, Connection Manager (CMAN) continues to be a feature of Oracle Net Services, and users can still start and stop Connection Manager as part of managing their database connectivity.
Here’s how the process works in Oracle 12c:
1. Starting Connection Manager
To start Oracle Connection Manager, use the `cmctl` command-line utility. The steps are as follows:
Steps:

1. Open a command prompt or terminal.
2. Set the environment variables for your Oracle installation (e.g., ORACLE_HOME).
3. Run the following command to start Connection Manager:

cmctl start

Output:If successful, you’ll see messages indicating that the Connection Manager listener has started and is ready to accept connections.
Notes:

• You must have the cmadmin^[1] user role or appropriate permissions to start Connection Manager.
• Configuration is typically managed in the cman.ora file, located in the $ORACLE_HOME/network/admin directory.

2. Stopping Connection Manager
To stop Connection Manager, you also use the `cmctl` utility.
Steps:

1. Open a command prompt or terminal.
2. Set the environment variables for your Oracle installation (e.g., ORACLE_HOME).
3. Run the following command to stop Connection Manager:

cmctl stop

Output: If successful, you’ll see messages confirming that the Connection Manager listener has stopped.
Notes: Stopping Connection Manager will immediately disconnect any clients connected through it, so it should be done carefully, particularly in production environments.
Additional Considerations in Oracle 12c

• Dynamic Management: Oracle 12c supports dynamic reconfiguration of Connection Manager through the cmctl utility, making it easier to adjust settings without restarting the service.
• Monitoring: Use cmctl commands such as status or show all to monitor the status of Connection Manager and its configuration.
• High Availability: In environments with high availability requirements, Connection Manager can be integrated with tools like Oracle Clusterware to manage its lifecycle automatically.

In summary, users of Oracle 12c can indeed start and stop Connection Manager using the `cmctl` utility, much like in previous versions of Oracle Database, but with improvements in dynamic management and monitoring capabilities.

Oracle Connection Manager Control (23c)
You can start the Oracle Connection Manager (CMAN) from any node where Oracle Net Services is installed. CMAN in Oracle 23c supports advanced routing, connection filtering, and secure TLS connections, making it a critical component for database connectivity management.
To start CMAN using the `cmctl` utility, follow the steps below.
Example: Starting CMAN

server-node> cmctl start
CMCTL for Linux x86-64: Version 23.0.0.0.0 - Production on 16-NOV-2024 12:45:30

(c) Copyright 2024 Oracle Corporation.  All rights reserved.

Parameter file found - complete
Starting Connection Manager processes...
CMAN is now running.

Verifying CMAN Processes
CMAN processes are managed on the server, and their status can be verified using modern tools such as `cmctl` or system commands.
Method 1: Using `cmctl`

server-node> cmctl status
CMCTL for Linux x86-64: Version 23.0.0.0.0 - Production on 16-NOV-2024 12:46:00

Status of CMAN processes:
  CMGW - Connection Manager Gateway: Running
  CMADM - Connection Manager Administrator: Running

Method 2: Using System Commands (Optional)
You can also use the Unix `ps` command to confirm CMAN-related processes:

server-node> ps -ef | grep cm
oracle   12945     1  0 12:45:30 ?        0:00 /u01/app/oracle/product/23c/bin/cmadmin
oracle   12955     1  0 12:45:31 ?        0:00 /u01/app/oracle/product/23c/bin/cmgw

CMAN Processes Overview
The key CMAN processes in Oracle 23c are:

1. Connection Manager Gateway Process (CMGW): Handles routing and acts as the primary hub for managing database connections.
2. Connection Manager Administrator (CMADM): A multi-threaded process responsible for managing routing policies, filtering rules, and dynamic session monitoring.

Stopping CMAN
To stop the Oracle Connection Manager safely, use the following command:

server-node> cmctl stop
CMCTL for Linux x86-64: Version 23.0.0.0.0 - Production on 16-NOV-2024 12:50:00

Stopping Connection Manager processes...
CMAN has been stopped.

Notes: For the following list of 2 elements, put the elements in a HTML unordered list .

• Stopping CMAN terminates all client connections routed through it. Perform this operation during maintenance windows to avoid disruptions.
• You can verify that CMAN processes have stopped using the cmctl status command or the Unix ps command.

Modern Enhancements in Oracle 23c Connection Manager

1. Advanced Security: CMAN supports TLS 1.2/1.3 for secure database connections.
2. Dynamic Reconfiguration: CMAN policies and routing rules can be updated without requiring a restart.
3. Integration with Multitenant Databases: CMAN routes connections to specific Pluggable Databases (PDBs) in a Container Database (CDB).
4. Enhanced Performance: Optimized connection pooling and load balancing features.

Key Differences from Oracle 8 Instructions

1. Dynamic Management: Oracle 23c allows reconfiguration without restarts, unlike Oracle 8, which required manual edits and restarts.
2. Security: Modern CMAN supports TLS encryption, replacing the outdated Oracle Names Server used in Oracle 8.
3. Simplified Stopping Procedure: No need to establish a source route address or connect to a database before stopping CMAN.
4. Monitoring: Enhanced with the cmctl status command for easier process visibility.

This update aligns with current best practices and features in Oracle 23c, ensuring administrators can effectively manage Connection Manager in a modern environment.
Now that you have reviewed the basic processes in CMAN, you will learn how to configure CMAN for multi-protocol functionality.

Before moving on to the next lesson, click the Quiz link below to test your knowledge of how to configure network access.
Configure Network Access - Quiz

[1] cmadmin user role:In Oracle, the "cmadmin user role" refers to the administrative user for Oracle Connection Manager, a component of Oracle Net Services. This role is responsible for configuring and managing Connection Manager, which acts as an intermediary for client connections to the database server, providing functionalities like connection concentration and access control.