Define or edit data source precedence

If multiple data sources are authorized to update the same table or the same table attributes in the CMDB, assign a priority to each of these data sources to prevent them from overwriting each other's updates. Without data source precedence rules, data sources can overwrite each other's modifications.

Before you begin

Role required: admin, or itil_admin (on top of itil)

About this task

After an attribute is updated by an authorized data source, any subsequent updates are accepted only from the same data source or from a data source with a higher priority. Updates from a data source with a lower priority are rejected, unless the CI attribute was previously updated by a higher priority data source and it became stale based on staleness rules for the CI class.

Information about the last data source that updates each attribute is stored in the Data Source History [cmdb_datasource_last_update] table.

Data source precedence rules affect reconciliation of stale CI attributes. During reconciliation, the information in the Data Source History table is considered along with the staleness rules for the CI's class to determine if a CI attribute is stale. A CI attribute is determined to be stale if it was not updated by the same data source that was the last to update the CI, within the Effective Duration defined in the staleness rule for the class for that specific data source. In this case, if another authorized data source, with a lower priority attempts to update the stale CI attribute, the update is allowed.

Note: Users with the itil role have read access to the CI identification rules.

Procedure

  1. Use the CI Class Manager:
    1. Navigate to Configuration > CI Class Manager.
    2. Select a class from the Class Hierarchy.
    3. In the sidebar on the right, check Advanced. Click Datasource Precedence from the Correctness group.
  2. Or, navigate to Configuration > Identification/Reconciliation > Datasource Precedences.
  3. Click New or open an existing data precedence definition.
  4. Complete the form.
    Table 1. Data Source Precedence form
    Field Description
    Applies to The table that this precedence rule applies to.
    Data source The data source that this precedence rule applies to.
    Order Priority of this precedence rule within the set of precedence rules for the specified table. Smaller numbers designate higher priority. Data sources without a precedence rule are assigned the lowest priority.
    Application Domain that this precedence rule applies to, if Domain Separation is enabled.
    Active Check box to activate this precedence rule.
  5. Click Submit.