Error: memcached flush_all not working

Solution for the "Memcached Flush_all Not Working" Error

The "memcached flush_all not working" error typically occurs when the flush_all command fails to clear the cache in a Memcached instance. This can be due to various reasons such as incorrect configuration, permission issues, or version incompatibilities.

Common Causes and Solutions

1. Incorrect Configuration:

• Ensure that the Memcached server is running and properly configured.
• Check the Memcached configuration file (usually memcached.conf) for any syntax errors or incorrect settings.
• Verify that the flush_all command is not disabled in the configuration file.

2. Permission Issues:

• Ensure that the user running the flush_all command has the necessary permissions to access and modify the Memcached instance.
• Check the permissions on the Memcached socket file (usually /tmp/memcached.sock) and ensure that the user has write access.

3. Version Incompatibilities:

• Verify that the Memcached client library and the Memcached server are compatible versions.
• Ensure that the client library supports the flush_all command.

Troubleshooting Steps

1. Check Memcached Status:

• Run the command memcached -vv to check the Memcached status and verify that it is running correctly.

2. Verify Flush_all Command:

• Run the command telnet localhost 11211 to connect to the Memcached server.
• Issue the command flush_all and check the response. If it fails, check the Memcached logs for errors.

3. Check Memcached Logs:

• Check the Memcached logs for any error messages related to the flush_all command.
• Verify that the logs are correctly configured and that log rotation is not causing issues.

4. Test with Memcached Client:

• Use a Memcached client library (e.g., pymemcache in Python) to test the flush_all command.
• Verify that the client library is correctly configured and that the flush_all command is supported.

Additional Tips

Use the -v Option:

• When running the memcached command, use the -v option to increase verbosity and get more detailed output.

Check Firewall Settings:

• Ensure that the firewall settings are not blocking the Memcached port (usually 11211).

Restart Memcached:

• If all else fails, try restarting the Memcached server to see if it resolves the issue.

By following these steps and troubleshooting tips, you should be able to identify and resolve the "memcached flush_all not working" error.