CMDB alert grouping — properties and functionality

  • Release version: Yokohama
  • Updated January 30, 2025
  • 3 minutes to read
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    Summary of CMDB alert grouping — properties and functionality

    CMDB alert grouping in ServiceNow enables efficient organization of alerts by leveraging Configuration Item (CI) relationships. This grouping enhances alert management effectiveness by correlating related alerts based on CMDB topology and relationship data.

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    Key Properties for Managing CMDB Alert Group Creation

    • Enable CMDB correlation (saanalytics.agg.querycmdbcorrelationenabled): Activates automatic use of CI relationships to aggregate and group alerts.
    • Max number of relations between CIs in a topology (saanalytics.agg.querycmdbgraphwalknodes): Sets how many hops between related CIs are considered when forming groups. Values above 4 may degrade performance.
    • Use all CMDB relations for group correlation (evtmgmt.relatedcisgetallrelationtypes): When true (default for new users), all relationship types are included in grouping. When false, only specified relationships are used, enabling finer control.

    Advanced Use Case Configuration for Automatic CMDB Alert Group Creation

    For scenarios requiring exclusion or fine-tuning of relationships in alert grouping, set evtmgmt.relatedcisgetallrelationtypes to false and configure the following properties:

    • Enable Suggested Relations (saanalytics.agg.querycmdbsuggestedrelationshipenabled): Uses specific relationships defined in the CMDB Group CI Relations [emsuggestedrelationtype] table. Add custom relationships here for inclusion.
    • Use containment metadata rules (evtmgmt.relatedcisusecontainmentrules): Applies host-containment relationships defined in Metadata Editor rules when forming groups. Enabled by default.
    • Enable filtering by dependent hosting rules (evtmgmt.relatedcisusehostingrules): Applies hosting relationships to control grouping based on which CIs host others. Hidden and enabled by default; add manually to change.
    • Ignore groups formed by applicative flow relations (saanalytics.agg.ignorecmdbapplicativeflow): Prevents grouping based on application service flow relations. Hidden and enabled by default; can be modified by adding the property.

    Performance Optimization Properties

    • Event Management CI Graph Reuse (saanalytics.applicativeflowrcenabled): Controls storage of CI relation maps for faster relation searches.
    • Graph reuse storage period (saanalytics.agg.querycmdbgraphreuseperiod): Defines how long relation maps are stored (default 86,400 seconds / 1 day). Setting to zero disables storage. This property must be added manually if customization is needed.

    Practical Implications for ServiceNow Customers

    By configuring these properties, customers can tailor alert grouping behavior to their CMDB structure and operational needs, improving alert relevance and reducing noise. Adjusting relationship types and hop limits allows balancing between thorough grouping and system performance. Advanced properties provide granular control over which CI relationships contribute to alert groups, supporting complex environments and use cases.

    Learn about the key properties and functionality of CMDB alert grouping, which facilitate efficient alert organization based on relationships and enhance the overall effectiveness of alert management.

    Properties for managing CMDB alert group creation

    Use the properties listed in the following tables to control CMDB alert group creation. For more information, see Configure scheduled job-based alert grouping.

    Property Setting

    Enable CMDB correlation

    sa_analytics.agg.query_cmdb_correlation_enabled

    Enable this property to automatically use CI relationships for alert aggregation, correlating alerts and creating CMDB alert groups.

    Max number of relations between CIs in a topology that form a CMDB group

    sa_analytics.agg.query_cmdb_graph_walk_nodes

    Set the maximum number of enabled relations between CIs in a topology that form a CMDB group.

    For example, if you set this property to 3, a CI associated with an alert will automatically be grouped with similar CIs within three hops or less.

    Note:
    This property setting impacts all types of relations used for alert aggregation. Using a value greater than 4 may negatively affect the performance of the alert aggregation job.

    Use all CMDB relations for CMDB group correlation

    evt_mgmt.related_cis_get_all_relation_types

    Set to true if you want to use all relationship types for CMDB grouping. The default setting for new users is that the option is set to true, meaning all relationship types are used for grouping. Set the property to false to filter the relations.

    Properties for managing automatic creation of CMDB alert groups for advanced use cases

    In some use cases, you may need to ignore or exclude certain CI relationships from automatic alert group creation. In this case, the evt_mgmt.related_cis_get_all_relation_types property must be set to false, and the properties in the below table must also be configured.
    Note:
    If the evt_mgmt.related_cis_get_all_relation_types property is set to false, and the relationship isn’t specified in the [em_suggested_relation_type] table, the relationship is not considered for alert aggregation.
    Table 1. Properties for managing automatic creation of CMDB alert groups for advanced use cases
    Property Setting

    Enable Suggested Relations for CMDB Correlation

    sa_analytics.agg.query_cmdb_suggested_relationship_enabled

    Keep this property enabled to use any suggested relationships defined in the CMDB Group CI Relations [em_suggested_relation_type] table when forming CMDB alert groups. To include a new relationship, add it to this table.

    This property is enabled by default.

    Use CMDB relationship based on host-containment Metadata rules

    evt_mgmt.related_cis_use_containment_rules

    Containment rules specify which configuration item classes can be contained within another item through a specific relationship when creating a service template.

    Keep this property enabled when forming CMDB alert groups to use any host-containment rules defined in the Metadata Editor. For more details, see CMDB dependent relationship rules.

    This property is enabled by default.

    Enable filtering by dependent relationship rules

    evt_mgmt.related_cis_use_hosting_rules

    Hosting rules define what classes of configuration items are hosted on other classes of configuration items.

    Keep this property enabled when forming CMDB alert groups to apply any hosting rules, which define which classes of configuration items are hosted on other classes.

    This property is hidden and enabled by default.
    Note:
    If you need to change the default value, add the property, as it does not exist in the instance by default. For more information on how to create a property, see Add a system property.

    Ignore CMDB alert groups from forming due to CI applicative flow relations

    sa_analytics.agg.ignore_cmdb_applicative_flow

    Set this property to true to prevent CMDB groups from forming based on applicative flow relations for CI relations in application services.

    This property is hidden and enabled by default.
    Note:
    If you need to change the default value, add the property, as it does not exist in the instance by default. For more information on how to create a property, see Add a system property.

    sa_analytics.applicative_flow_rc_enabled

    This property is hidden and enabled by default.

    Event Management stores a map of related CIs in the Event Management CI Graph Reuse [em_ci_graph_reuse] table for each processed CI. You can adjust the storage period by modifying the sa_analytics.agg.query_cmdb_graph_reuse_period property, with the default set to one day (86,400 seconds). This process enhances the search performance of relations in the CMDB. To disable the storage process during advanced use-case configurations, set the property value to zero.
    Note:
    If you need to change the default value, add the sa_analytics.agg.query_cmdb_graph_reuse_period property, as it does not exist in the instance by default. For more information on how to create a property, see Add a system property.