Troubleshooting ScyllaDB Streaming Display Issues

by Alex Johnson 50 views

Is your ScyllaDB streaming progress stubbornly refusing to show up on your dashboard? You're not alone! Many users have encountered this issue, where the streaming percentage remains static despite ongoing data migrations or repairs. This article dives into the potential causes behind this frustrating problem and offers practical steps to diagnose and resolve it. We'll explore the intricacies of ScyllaDB monitoring, examine common configuration pitfalls, and delve into the core mechanisms that govern streaming visibility. Whether you're a seasoned ScyllaDB administrator or just starting your journey, this guide will equip you with the knowledge and tools to get your streaming metrics back on track.

Understanding the Issue: No Streaming Data on Your Dashboard

Streaming is a critical operation in ScyllaDB, essential for tasks like adding new nodes (RBNO - Replace Bootstrap Node Operation), performing repairs, and migrating tablets. When streaming works correctly, your monitoring dashboard should reflect the progress, showing the percentage completed and the amount of data transferred. However, when this data is missing, it can be difficult to assess the health and performance of your cluster.

If you're experiencing a situation where the streaming percentage on your ScyllaDB dashboard remains unchanged, even during known streaming operations like RBNO, tablet migration, or repairs, you've landed in the right place. This issue, reported by users across different ScyllaDB versions (including 2025.x) and monitoring setups (like Scylla-Monitoring 4.12.1 and earlier), can stem from several factors. The root cause might lie in the monitoring configuration, the core ScyllaDB settings, or even a combination of both. Pinpointing the exact reason requires a systematic approach, which we'll break down in this article. We'll guide you through the troubleshooting process, exploring common causes, and offering solutions to get your ScyllaDB streaming metrics back on track. By the end of this guide, you'll have a clearer understanding of how ScyllaDB streaming is monitored and the steps you can take to ensure accurate data visibility.

Potential Causes and Troubleshooting Steps

Let’s explore the potential causes behind the missing streaming data and the troubleshooting steps you can take to identify the problem. We'll cover everything from basic checks to more in-depth investigations, ensuring you have a comprehensive toolkit for resolving this issue. Remember, a methodical approach is key to successful troubleshooting. Start with the simpler solutions and gradually move towards more complex diagnostics.

1. Verify Basic Connectivity and Metrics Collection

First, let's cover the basics. It might sound obvious, but ensuring your monitoring system can communicate with your ScyllaDB nodes is paramount. Are the nodes reachable? Is the monitoring agent properly configured to collect metrics from ScyllaDB? A simple connectivity test can save you hours of chasing down more complex issues.

  • Check Network Connectivity: Use tools like ping or traceroute to verify that your monitoring server can reach the ScyllaDB nodes on the network. Firewalls or network configurations might be blocking the necessary ports.
  • Confirm Monitoring Agent Status: Ensure the monitoring agent (e.g., Prometheus node exporter) is running on each ScyllaDB node. Check the agent's logs for any errors or warnings that might indicate a problem.
  • Verify ScyllaDB Metrics Endpoint: ScyllaDB exposes metrics via an HTTP endpoint (usually on port 9180). Use curl or a similar tool to query this endpoint and confirm that metrics are being returned. For example: curl http://<scylla-node-ip>:9180/metrics

If you can't connect to the nodes or retrieve metrics, you've identified a fundamental problem that needs to be addressed before you can proceed further. This is often the simplest fix, but it's a crucial step in the troubleshooting process. Remember, no data can flow if the connection is broken!

2. ScyllaDB Monitoring Version Compatibility

Ensure that your ScyllaDB Monitoring version is compatible with your ScyllaDB version. Incompatibilities between monitoring tools and the database itself can lead to incorrect data display or a complete lack of metrics. Older monitoring versions might not be aware of the latest metrics exposed by ScyllaDB, or vice versa.

  • Review Compatibility Matrix: Consult the official ScyllaDB documentation or the ScyllaDB Monitoring documentation for a compatibility matrix. This will clearly outline which monitoring versions are supported for your ScyllaDB version (in this case, 2025.x).
  • Upgrade or Downgrade if Necessary: If you find an incompatibility, plan for an upgrade or downgrade of either ScyllaDB or the monitoring tools. Always follow the recommended upgrade/downgrade procedures to avoid data loss or service disruption.
  • Check Release Notes: Release notes for both ScyllaDB and ScyllaDB Monitoring often contain valuable information about compatibility and known issues. Review them carefully for any clues related to your problem.

Keeping your ScyllaDB and monitoring tools in sync is essential for a smooth operation. Compatibility issues are a common culprit behind metric display problems, so this is a vital area to investigate.

3. Investigate Prometheus Configuration

Prometheus is a popular choice for collecting and storing metrics in ScyllaDB environments. If you're using Prometheus, a misconfigured Prometheus setup can prevent streaming metrics from being displayed. Let's look at key areas within Prometheus that need scrutiny.

  • Target Configuration: Ensure that Prometheus is correctly configured to scrape metrics from your ScyllaDB nodes. Check the prometheus.yml file for the correct target IPs and ports.
  • Service Discovery: If you're using service discovery (e.g., Kubernetes service discovery), verify that Prometheus is correctly discovering your ScyllaDB nodes.
  • Relabeling Rules: Review your relabeling rules in prometheus.yml. Incorrect relabeling can drop or modify important metrics, including those related to streaming. Pay close attention to any rules that might be filtering out scylla_streaming_* metrics.
  • Query Issues: Sometimes, the issue isn't the data collection but the queries used to display the data. Examine the queries in your Grafana dashboards (or other visualization tools) to ensure they are correctly targeting the streaming metrics.

Example Prometheus Configuration Snippet:

Here’s an example of a Prometheus configuration snippet for scraping ScyllaDB metrics:

scrape_configs:
  - job_name: 'scylla'
    static_configs:
      - targets: ['<scylla-node-ip>:9180', '<another-scylla-node-ip>:9180']

This snippet defines a job named scylla that scrapes metrics from two ScyllaDB nodes. Make sure your configuration aligns with your ScyllaDB cluster setup.

4. Grafana Dashboard Issues

Grafana dashboards are commonly used to visualize ScyllaDB metrics. Problems within the Grafana dashboard itself can lead to streaming data not being displayed, even if the metrics are being collected correctly by Prometheus. It's crucial to investigate the dashboard configuration and ensure it's correctly configured to display the relevant data.

  • Query Verification: Carefully examine the queries used in your Grafana panels. Are they correctly targeting the scylla_streaming_* metrics? Are there any typos or logical errors in the queries?

    • Example Query: A typical query to display streaming progress might look like this:
    sum(scylla_streaming_session_progress) by (instance)

    Make sure the query aligns with the metrics exposed by your ScyllaDB version.

  • Variable Scope: If you're using variables in your dashboards (e.g., to filter by node), ensure they are correctly configured and that the selected values are valid.

  • Panel Configuration: Check the panel configuration settings, such as the time range, data source, and visualization type. Incorrect settings can prevent data from being displayed.

  • Dashboard Import/Update Issues: If you've recently imported or updated a dashboard, there might be issues with the import process or changes in the dashboard structure. Try reverting to a previous version or re-importing the dashboard.

5. ScyllaDB Configuration and Metrics Exposure

ScyllaDB itself needs to be configured to expose streaming metrics. While ScyllaDB generally exposes these metrics by default, it's worth verifying the configuration to rule out any unexpected settings.

  • Metrics Endpoint Enabled: Double-check that the metrics endpoint is enabled in your ScyllaDB configuration (scylla.yaml). The relevant settings are usually under the prometheus section.
  • Streaming Metrics Enabled: While less common, there might be settings that control the exposure of specific metrics. Consult the ScyllaDB documentation for your version to see if there are any configuration options related to streaming metrics.
  • Resource Constraints: In extreme cases, resource constraints (e.g., CPU or memory limits) on the ScyllaDB nodes could affect the ability to collect and expose metrics. Monitor resource utilization on your nodes to rule out this possibility.

6. Investigate Streaming Operations

Sometimes, the issue isn't the monitoring but the streaming operations themselves. If streaming isn't happening as expected, or if it's completing too quickly, the dashboard might not reflect the progress accurately. Deep dive into the health and activity of your ScyllaDB cluster.

  • Check Streaming Status: Use nodetool commands (like nodetool netstats) to verify that streaming operations are indeed in progress. This will give you a direct view of the streaming activity within ScyllaDB.

    • Example Command: nodetool netstats

  • Analyze Logs: ScyllaDB logs can provide valuable insights into streaming operations. Look for any errors or warnings related to streaming or data migrations.

  • Repair Service: If you suspect issues with repairs, check the status of the repair service. Are repairs running as expected? Are there any errors in the repair logs?

  • Data Volume: If the data volume being streamed is small, the operation might complete very quickly, making it difficult to observe progress on the dashboard. This is less of a problem but something to keep in mind.

7. ScyllaDB Internals and Potential Bugs

In rare cases, the issue might stem from a bug within ScyllaDB itself. While this is less likely, it's important to consider this possibility, especially if you've exhausted all other troubleshooting steps. You should consult with ScyllaDB support or their community forums if you suspect a bug.

  • Search for Known Issues: Check the ScyllaDB issue tracker and forums for any reports of similar problems. There might be a known bug with a workaround or a fix available in a later version.
  • Engage with the Community: Post your issue on the ScyllaDB forums or community channels. Other users might have encountered the same problem and can offer insights or solutions.
  • Contact ScyllaDB Support: If you have a ScyllaDB support contract, reach out to their support team. They have deep expertise and can help diagnose complex issues.

Conclusion: Restoring Visibility to Your Streaming Operations

Troubleshooting ScyllaDB streaming display issues requires a systematic approach, combining basic checks with more in-depth investigations. By methodically working through the steps outlined in this article, you can pinpoint the root cause and restore visibility to your streaming operations. Remember to verify connectivity, check version compatibility, scrutinize Prometheus and Grafana configurations, and investigate ScyllaDB internals. With persistence and a keen eye for detail, you'll be back on track in no time.

For more information on ScyllaDB monitoring and troubleshooting, refer to the official ScyllaDB Documentation. This comprehensive resource provides in-depth guidance on all aspects of ScyllaDB administration and monitoring.