报错warning:root:cannot Call Open Vswitch: Ovsdb-server.service Is Not Running.

6 min read Oct 03, 2024

报错warning:root:cannot Call Open Vswitch: Ovsdb-server.service Is Not Running.

Troubleshooting "warning:root:cannot call open vswitch: ovsdb-server.service is not running" Error

This error message, "warning:root:cannot call open vswitch: ovsdb-server.service is not running," is a common issue encountered when working with Open vSwitch (OVS) on Linux systems. It indicates that the Open vSwitch Database Server (ovsdb-server) service, which is responsible for managing OVS configuration data, is not running. This can prevent Open vSwitch from functioning properly.

Let's delve into the possible reasons for this error and explore practical solutions to get your Open vSwitch up and running.

Understanding the Problem

Open vSwitch relies on the ovsdb-server to manage its configuration and data. This server acts as a central repository for all OVS settings, including network bridges, ports, and flows. When the ovsdb-server is not running, Open vSwitch cannot access this data, resulting in the "cannot call open vswitch" error.

Common Causes

Here are some common reasons why the ovsdb-server might not be running:

Service Not Started: The ovsdb-server service might not have been started after installing Open vSwitch.
Service Crashed: The ovsdb-server process could have crashed due to a system issue or a faulty configuration.
Service Disabled: The ovsdb-server service might have been disabled, preventing it from starting automatically.
Dependency Issues: Other services that Open vSwitch depends on, such as the database backend, might not be running.

Troubleshooting Steps

Here's a step-by-step guide to troubleshoot and resolve the "cannot call open vswitch" error:

Check the Service Status:
- Command: systemctl status ovsdb-server
- Output: The output will show if the service is running, stopped, or in a failed state.
Start the Service:
- Command: systemctl start ovsdb-server
- Output: If the service starts successfully, you can attempt to use Open vSwitch commands again.
Enable the Service:
- Command: systemctl enable ovsdb-server
- Output: This ensures that the ovsdb-server service starts automatically on system boot.
Check the Logs:
- Command: journalctl -u ovsdb-server
- Output: Review the logs for any error messages or clues about why the service failed to start.
Verify Database Configuration:
- Command: ovsdb-server --help
- Output: This command provides information about the default database backend used by ovsdb-server. Make sure the backend is configured and running correctly.
Address Dependency Issues:
- Command: systemctl status [dependent services]
- Example: systemctl status postgresql (if PostgreSQL is used as the backend)
- Output: Check the status of services that OVS might depend on and start or enable them if necessary.

Example Scenario

Let's consider a scenario where the ovsdb-server service has been disabled.

Check the Service Status:

systemctl status ovsdb-server

Output:

● ovsdb-server.service - Open vSwitch Database Server
  Loaded: loaded (/usr/lib/systemd/system/ovsdb-server.service; disabled; vendor preset: enabled)
  Active: inactive (dead)

This output indicates that the ovsdb-server service is not running and disabled.

Enable and Start the Service:
```
systemctl enable ovsdb-server
systemctl start ovsdb-server
```
After running these commands, check the service status again to verify that it's running.

Additional Tips

Firewall Rules: Ensure that your firewall rules allow access to the port used by ovsdb-server (typically 6640).
Resource Limitations: Check if your system has enough resources (memory, CPU) for the ovsdb-server to run properly.
Database Corruption: In rare cases, database corruption might prevent the ovsdb-server from starting. If you suspect corruption, consider restoring the database from a backup.

Conclusion

The "warning:root:cannot call open vswitch: ovsdb-server.service is not running" error signals that the Open vSwitch Database Server is not operational. By following the troubleshooting steps outlined above, you can identify and resolve the underlying issue, ensuring the proper functioning of Open vSwitch on your system. Remember to check the service status, logs, and relevant dependencies for a comprehensive diagnosis.