My Iot hub is buffering Data

Hi Helix Sense

Here are few reasons behind buffering and remedials to fix it.

Possible Reasons:

1. Check Network Connectivity: Ensure that there are no network issues causing the buffering. Poor connectivity can lead to data being buffered until a stable connection is re-established.
2. Telemetry Queue Timeout: The Azure IoT Device Client SDK has a telemetry queue with a configurable timeout. By default, this timeout is set to 4 minutes. If a telemetry message is not sent within this timeout, it will trigger a callback with the result IOTHUB_CLIENT_CONFIRMATION_MESSAGE_TIMEOUT. You can adjust this timeout setting to better suit your needs. Reference on Telemetry Que timeout
3. Message Size , Quota and Throttling: Ensure that the total message size, including any enrichments, does not exceed 256 KB. If a message exceeds this size, the IoT Hub will throw an exception. Additionally, check if you have exceeded the allocated quota for messages on the IoT Hub. Reference Quota and Throttling
4. Buffering and Batching: The Azure IoT SDKs provide solutions for bandwidth savings, such as buffering and batching. Buffering allows the device to store data when connectivity is poor, and batching reduces the number of messages transmitted by merging information from multiple messages into a single batch. Ensure that these settings are configured correctly for your scenario Reference on Buffering

Solution:

1. Inspect IoT Hub Metrics: Look at metrics like message count, latency, and dropped messages in Azure Monitor. If there is no drop in throughput, check your routing rules and ensure they are working as expected. Please check if you are facing any throttling error from activities or metrics tab and upgrade your IOT Hub if needed.
2. Check Logging: Enable debug logs for IoT Hub and your devices to pinpoint where delays occur. Reference on logging library
3. Test a Direct Send: Try sending a test message and monitor whether it gets delayed.
4. Optimize Message Routing: Modify IoT Hub message routing to avoid unnecessary buffering if batching is enabled. Enable fall back routing endpoints.
5. Modify the data retention period in Azure portal to clear out very old data post retention period. In the "Data Retention" blade, you can set the retention time for your data. You can choose to keep the data for a specific number of days (e.g. 7 days) or to delete it immediately. Once you have set the retention time, click on "Save" to apply the changes. Reference thread on Data retention
6. Ensure Network Stability: If latency is suspected, check network performance.
7. Diagnostic Logs: Use Azure Monitor Logs to troubleshoot connectivity issues. Create a diagnostic setting to send IoT Hub Connections logs to a Log Analytics workspace. This can help you identify common issues and understand the reasons behind device disconnects. Reference document on monitoring IOT hub
8. SDK and Firmware Updates: Ensure that you are using the latest version of the Azure IoT SDK and that your device firmware is up to date. Sometimes, issues can arise from outdated software Reference on SDKs

Hope above pointes help understand and resolve your

Thank you.

Hello Helix Sense,

welcome to this moderated Azure community forum.

Better questions with more information lead to better answers from our community members.

Please provide information about the steps you have taken, the guide you follow, and the behavior you see so fellow members can understand your question better.

The IoT Hub buffers incoming data according to the retention time set in the configuration (up to 7 days).

The time the data flows through the IoT Hub is minimal so, after arrival, there should be no noticeable delay. You can check the iothub-enqueuedtime as a reference.

Please check the flow with eg. a custom route to an EventHub (it has a Data Explorer so you can see message arriving in real time) so you should see a minimal delay there.

If you reference the 'default eventhub compatible endpoint' of the IoT HUb being 'slow', there are two things to take into consideration:

• Each 'consumer' of this endpoint (eg. An Azure Function, Azure Data Explorer, or Azure Stream Analytics, or test tooling like VS Code) must get its own consumer group so each consumer gets its own stream of messages (otherwise errors can occur)
• If you add custom routes to the IoT Hub, this default endpoint will turn into a fall back scenario. Read the text on the routing page for details. The simple solution is to add an extra route pointing to the default endpoint and the default endpoint flow is restored.

Let us know if this helps.

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