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diff --git a/health/guides/vernemq/vernemq_mqtt_pubrel_sent_reason_unsuccessful.md b/health/guides/vernemq/vernemq_mqtt_pubrel_sent_reason_unsuccessful.md deleted file mode 100644 index 18e85e12a..000000000 --- a/health/guides/vernemq/vernemq_mqtt_pubrel_sent_reason_unsuccessful.md +++ /dev/null @@ -1,49 +0,0 @@ -### Understand the alert - -This alert is related to VerneMQ, a high-performance MQTT broker. It monitors the number of unsuccessful v5 `PUBREL` packets sent in the last minute. If you receive this alert, it means that there was an issue with sending `PUBREL` packets in your VerneMQ instance. - -### What does PUBREL mean? - -`PUBREL` is a type of MQTT control packet that indicates the release of an application message from the server to the client. It is the third message in the QoS 2 (Quality of Service level 2) protocol exchange, where QoS 2 ensures that a message is delivered exactly once. An unsuccessful v5 `PUBREL` packet means that there was an error during the packet processing, and the message wasn't delivered to the client as expected. - -### Troubleshoot the alert - -1. Check the VerneMQ logs: - - VerneMQ logs can give you valuable information about possible errors that might have occurred during the processing of `PUBREL` packets. Look for any error messages or traces related to the `PUBREL` packets in the logs. - - ``` - sudo journalctl -u vernemq -f - ``` - - Alternatively, if you're using a custom log location: - - ``` - tail -f /path/to/custom/log - ``` - -2. Check the MQTT client-side logs: - - Check the logs of the MQTT client that might have caused the unsuccessful `PUBREL` packets. Look for any connection issues, error messages, or traces related to the MQTT protocol exchanges. - -3. Ensure proper configuration for VerneMQ: - - Verify that the VerneMQ configuration settings related to QoS 2 protocol timeouts and retries are correctly set. Check the VerneMQ [documentation](https://docs.vernemq.com/configuration) for guidance on the proper configuration. - - ``` - cat /etc/vernemq/vernemq.conf - ``` - -4. Monitor VerneMQ metrics: - - Use Netdata to monitor VerneMQ metrics to analyze the MQTT server's performance and resource usage. This can help you identify possible issues with the server. - -5. Address network or service issues: - - If the above steps don't resolve the alert, look for possible network or service-related issues that might be causing the unsuccessful `PUBREL` packets. This could require additional investigation based on your specific infrastructure and environment. - -### Useful resources - -1. [VerneMQ - Official Documentation](https://docs.vernemq.com/) -2. [MQTT Essentials: Quality of Service 2 (QoS 2)](https://www.hivemq.com/blog/mqtt-essentials-part-6-mqtt-quality-of-service-levels/) -3. [Netdata - VerneMQ monitoring](https://learn.netdata.cloud/docs/agent/collectors/go.d.plugin/modules/vernemq)
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