Identifying related alerts in log data by using log correlators in Health Log Analytics

  • Release version: Australia
  • Updated March 12, 2026
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    Summary of Identifying related alerts in log data by using log correlators in Health Log Analytics

    Health Log Analytics uses log correlators to detect relationships between alerts in log data, helping you determine if an alert is part of a broader issue. Correlators identify common keys or values appearing across multiple log sources, such as network interface IDs or service names, to reveal correlated alerts that may indicate systemic problems.

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    Key Features

    • Types of Log Correlators:
      • Free text correlators: Analyze unstructured terms within the log message text, such as unique system, application, or service names relevant to your environment (e.g., “teatime”). These help detect alerts linked by textual content not captured as structured metadata.
      • Log property correlators: Analyze structured metadata fields in log lines, such as service instance names, interface IDs, or request IDs, to find correlations across log sources.
    • Scope Control: You can configure correlators to analyze:
      • Only new log sources created after activation
      • All existing and future log sources
      • Specific log sources of your choosing
    • Customization: The base system provides built-in correlators, and you can define custom correlators tailored to your business context and log sources.
    • Source Exclusion: You can exclude specific log sources from correlator analysis to prevent irrelevant data from affecting alert correlations.

    Practical Benefits for ServiceNow Customers

    By leveraging log correlators in Health Log Analytics, you can more effectively identify when multiple alerts are related, streamlining root cause analysis and reducing alert noise. Custom correlators enable you to tailor correlation detection to your unique environment, improving the accuracy and relevance of alert grouping. Source inclusion and exclusion controls offer flexibility to focus analysis on critical data streams.

    In Health Log Analytics, log correlators are keys or values in log data that detect correlations between alerts to help you determine whether an alert is part of a larger issue. For example, a log correlator could detect when the interface ID of a particular network device occurs simultaneously in multiple warnings across different service instances.

    You can identify related alerts in your log data by using log correlators. The base system includes several log correlators, and you can define custom correlators for a specific log source, all log sources, or only log sources created after the correlator is activated.

    Most log lines include a metadata portion plus a message portion. Some log lines, however, include only message text with metadata included in the text. The two types of log correlators, free text correlators and log property correlators, analyze the different portions of each log to identify relationships between log data from multiple log sources.

    Free text correlators

    Free text correlators analyze the text within the log message portion of log lines that are associated with an anomaly. The system uses free text correlators to identify correlations between alerts. You use free text correlators to add a term that you expect to appear within log messages. A good choice is a term that is not structured and would not otherwise be extracted as a log property. For example, “policy-id” or “ thread-id”.

    You also typically add free text correlators for the names of systems, applications, and services that are unique to your environment. Because such a value can be referred to by multiple sources, layers, middleware, or databases, the free text correlator can be an effective detector of correlated alerts. For example, if your organization's service is called TeaTime, then you might add "teatime" as a free text correlator. The correlator would identify alerts that are related because they were generated for resources that support the TeaTime service, such as a database lock or a connection failure between TeaTime components.

    Log property correlators

    Log property correlators analyze the metadata portion of log lines. For example, the correlator can analyze the name of a service instance, the interface ID of a network device, or the request ID of a web-facing component. A log property correlator could flag a correlation when the interface ID of a network device simultaneously occurs in multiple warnings in different log sources. Log property correlators are specific to the business context of your environment.

    You can specify the set of log sources whose log data are analyzed by a log correlator. Choices are as follows:
    • Only new sources: The system applies the log correlator only to log lines from log sources that were created after this log correlator is activated.
    • All sources: The system applies the log correlator to log lines from all log sources.
    • Specified source: For a log correlator, the system analyzes only log lines from the log source that you specify.