Log correlators for identifying related alerts

  • Release version: Yokohama
  • Updated March 12, 2026
  • 2 minutes to read
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    Summary of Log correlators for identifying related alerts

    In Health Log Analytics, log correlators are essential tools that detect relationships between alerts by identifying common keys or values within log data. They help ServiceNow customers determine whether individual alerts are part of a broader issue, improving incident analysis and response. The system provides built-in correlators and allows customers to create custom ones tailored to specific log sources or environments.

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    Key Features

    • Types of Log Correlators:
      • Free Text Correlators: Analyze unstructured text within the log message portion to find terms unique to your environment, such as service or application names (e.g., “TeaTime”), enabling detection of related alerts across diverse components.
      • Log Property Correlators: Examine structured metadata in log lines, like service instance names or network interface IDs, to correlate alerts based on business-contextual properties.
    • Scope Configuration: You can specify which log sources a correlator applies to:
      • Only new sources created after correlator activation
      • All log sources
      • A specific, specified log source
    • Custom Correlators and Exclusions: Customers can define custom correlators to fit their unique environment and exclude specific log sources from analysis to focus correlations effectively.

    What You Can Expect

    By leveraging log correlators, ServiceNow customers can more accurately identify clusters of related alerts, improving root cause analysis and operational efficiency. Customizing correlators to your environment ensures relevant correlations, aiding faster detection of systemic issues across services and infrastructure components.

    In Health Log Analytics, log correlators are keys or values in log data that detect correlations between alerts. These correlations 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 service instances.

    You can identify related alerts in your log data by using log correlators. The base system includes several log correlators. 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 different portions of each log to identify relationships between data from multiple 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. For example, 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.