Monitoring data usage in Hermes

  • Release version: Yokohama
  • Updated April 28, 2025
  • 2 minutes to read
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    Summary of Monitoring data usage in Hermes

    The Hermes Usage Dashboard enables ServiceNow customers to monitor data usage within the Hermes cluster over time. It tracks the total size of messages sent to Hermes by aggregating the key size and message size, providing insights into data inflow measured in megabytes. This monitoring helps understand how much data applications produce and identify usage trends.

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    Key Features

    • Usage Visualization: View data usage trends for all topics or individual topics within Hermes, with the ability to compare topics belonging to the same application.
    • Data Aggregation: Data is collected hourly and aggregated into daily or monthly summaries depending on the selected date range (daily for under 60 days, monthly for over 60 days), allowing for trend analysis over time.
    • Role-based Access: Access to the Usage Dashboard requires either the hermesadmin or admin role.
    • Retention: Usage metric data is retained for up to 12 months.
    • Reports and Metrics: The dashboard displays metrics sourced from the hermesusagemetrics table, including total megabytes produced, usage trends for selected topics, and comparative topic usage data.

    Practical Use Cases

    • Monitor and analyze data usage trends for specific applications or topics to detect increases, decreases, or unusual spikes and drops.
    • Validate if application data production aligns with Hermes support by identifying declining data usage.
    • Compare data usage across topics within the same application to optimize resource allocation and performance.

    Access and Navigation

    To access the Hermes Usage Dashboard, navigate within ServiceNow to All > Hermes Messaging Service > Usage Dashboard. Users with appropriate roles can then explore detailed insights into data usage patterns.

    Monitor data usage in Hermes over time.

    Monitor the amount of data that is produced to the Hermes cluster over time in the Hermes Usage Dashboard.

    Usage data is calculated by aggregating the size of all messages sent to the cluster. The size for each message is determined by combining the key size, if present, and the actual size of the message sent to the Hermes cluster. For example, if a 100 MB message is sent to the cluster with a 2 MB key size, 102 MB usage is recorded for the message.

    Key benefits

    • Monitor Hermes performance with insights into data inflow in megabytes for a specified time period.
    • Visualize data usage over time for all topics or a single topic.
    • Compare data usage for topics that belong to an application.
    Figure 1. Hermes Usage Dashboard
    Hermes Metrics Dashboard.

    Required roles

    Either the hermes_admin or admin role is required to view the Hermes Usage Dashboard.

    Accessing the Hermes Usage Dashboard

    View usage by navigating to All > Hermes Messaging Service > Usage Dashboard.

    Use cases

    • Monitor data usage for an application. Determine if usage has increased or decreased over time.
    • View data usage for a specific topic. Determine if usage patterns changed by looking for spikes or drops in usage.
    • Look for decreased usage over time to determine if your application is producing data that isn't supported by Hermes.
    • Compare data usage for topics in a single application or all applications that belong to you.

    Reports

    Data displayed in the Hermes Metrics Dashboard is collected from the Hermes usage metrics [hermes_usage_metrics] table.
    • Metric data is captured hourly, with each collection point reflecting the latest value recorded within that hour.
    • Metric data is aggregated and displayed over time. This means the dashboard enables you to view an overall trend rather than precise moment-to-moment traffic.
    • Metric data displayed on the dashboard is initially aggregated daily. Depending on the date range you select, the dashboard dynamically adjusts its view. For example, for ranges greater than 60 days, it presents the data in monthly summaries. For ranges less than 60 days, it displays daily summaries.
    • Metric data is retained for 12 months.
    Title Type Source table Description
    Total Megabytes In Single score Hermes usage metrics [hermes_usage_metrics] table View the aggregated total of data produced to Hermes in megabytes.
    Usage trends Trend Hermes usage metrics [hermes_usage_metrics] table Monitor data usage in terms of bytes in for selected topics over time.
    Topic Usage Data Bar Hermes usage metrics [hermes_usage_metrics] table Compare data usage for each topic over time.