Monitoring data usage in Hermes

  • Release version: Zurich
  • Updated July 31, 2025
  • 2 minutes to read
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    Summary of Monitoring data usage in Hermes

    The Hermes Usage Dashboard in ServiceNow Zurich release enables monitoring of data usage in the Hermes messaging cluster over time. It aggregates the size of all messages sent to the Hermes cluster, combining both message key size and message payload size to calculate total data usage. This monitoring helps customers track data inflow in megabytes for specific time periods and topics.

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    Key Features

    • Data Usage Visualization: View usage trends for all topics collectively or individual topics within the Hermes cluster.
    • Application-Level Comparison: Compare data usage across topics belonging to a single application to identify usage patterns or anomalies.
    • Dynamic Time Range Aggregation: The dashboard adjusts data granularity based on the selected date range—daily summaries for under 60 days and monthly summaries for over 60 days.
    • Data Retention: Usage metrics are retained for 12 months, supporting historical analysis.
    • Role-Based Access: Access requires either the hermesadmin or admin role to ensure appropriate permissions.

    Practical Uses

    • Monitor overall data throughput to the Hermes cluster and detect significant spikes or drops in message volume.
    • Analyze usage trends over time to determine whether application data production is increasing, decreasing, or remaining consistent.
    • Investigate specific topics to understand their contribution to total data usage and identify potential issues or inefficiencies.
    • Compare data usage across topics within your applications to optimize message production and troubleshoot anomalies.

    Data and Reporting Details

    Usage metrics are sourced from the hermesusagemetrics table and captured hourly, reflecting the latest value within each hour. The dashboard presents aggregated data to show overall trends rather than real-time traffic. Key metrics include:

    • Total Megabytes: Aggregated volume of data sent to Hermes in megabytes.
    • Usage Trends: Data inflow over time for selected topics.
    • Topic Usage Data: Comparative data usage per topic across time.

    Accessing the Dashboard

    Users with the hermesadmin or admin roles can access the Hermes Usage Dashboard by navigating to All > Hermes Messaging Service > Usage Dashboard within the ServiceNow interface.

    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.