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Duplicate CIs

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Duplicate CIs

When the instance encounters duplicate CIs during identification and reconciliation, it groups each set of duplicate CIs into a de-duplication task for review and remediation.

De-Duplication tasks

De-duplication tasks provide details about the duplication, including a list of all the duplicate CIs. Review the details of each duplicate CI in the task and the data that was used to determine that the CI is a duplicate.

From a de-duplication task, you can run the Duplicate CI Remediator wizard to reconcile a set of duplicate CIs into a single CI, eliminating the duplication.

Duplicate CI Remediator

The Duplicate CI Remediator is a wizard-like tool that you can use to reconcile a set of duplicate CIs associated with a de-duplication task. You can choose one of the duplicate CIs to retain as an active CI, and then decide how to process the rest of the duplicate CIs. The Duplicate CI Remediator lets you set reconciliation options for attributes, relationships, and related items.

For information about using the Duplicate CI Remediator, see Remediate a de-duplication task.

Properties that affect processing of duplicate CIs

During CMDB Identification, processing of sets of duplicate CIs is determined by:
  • Property glide.identification_engine.skip_duplicates (true by default).
  • Property glide.identification_engine.skip_duplicates.threshold (5 by default).
  • Number of duplicate CIs in a set.

For information about how these properties affect the management of duplicate CIs, see Detecting duplicate CIs.

Master CI

The master CI plays an important role in the remediation of duplicate CIs. The master CI is a single CI from a set of duplicate CIs, that remains active while the rest of the duplicate CIs in the set are potentially retired, deleted, or reconciled into the master CI. Using the Duplicate CI Remediator, you can select a master CI for a set of duplicate CIs associated with a de-duplication task.

The duplicate_of attribute in duplicate CIs, is used to store a reference to the master CI. For duplicate CIs which existed in an instance that was upgraded to the New York release or later, the master CI is unknown. After upgrade, duplicate_of for those duplicate CIs is set to 'Unknown', indicating that the CI is a duplicate but the master CI is unknown.

Duplicate CIs set
Before remediation, the CIs in a duplicate CIs set are all duplicates of each other. After remediation, a set of duplicate CIs consists of one master CI, and any number of CIs, each considered a duplicate of the master CI. The duplicate_of attribute of the master CI is empty. The duplicate_of attribute for all the rest of the duplicate CIs in the set, is a reference to the master CI of the set.
If you attempt to modify the value of duplicate_of directly on a CI form or by using a script, the following restrictions are enforced to ensure data integrity:
  • A CI cannot be its own master CI (you cannot set a CI as a duplicate of itself).
  • A CI and its master CI cannot be from different domains.
  • The duplicate_of attribute of the master CI cannot reference any CI as its master CI (you cannot set a CI as a duplicate of another duplicate CI to create a chain of duplicate CIs).

    • If you attempt to set a CI as a duplicate of another duplicate CI, then the CI is set as a duplicate of the master CI of the duplicate CI you are trying to set. If the master CI of the duplicate CI you are trying to set is 'Unknown', the operation fails.

      Table 1. Example: Attempt to set a CI as duplicate of another duplicate CI
      CIs Attempted setting Result (System enforced)

      CI1: duplicate_of = empty

      CI2: duplicate_of = CI3

      CI3: Master CI

      CI1: duplicate_of = CI2

      CI1: duplicate_of = CI3

      CI2: duplicate_of = CI3

      CI3: Master CI

      If CI2 is a duplicate of 'Unknown', the operation fails.
    • If a master CI becomes a duplicate of another CI, then it can no longer be a master CI. All CIs that were duplicates of that master CI are set as duplicates of the new master CI.

      Table 2. Example: Attempt to set a master CI as duplicate of another CI
      CIs Attempted setting Result (System enforced)

      CI1: duplicate_of = CI4

      CI2: duplicate_of = CI4

      CI3: duplicate_of = CI4

      CI4: Master CI

      CI5: duplicate_of = empty

      CI4: duplicate_of = CI5

      CI1: duplicate_of = CI5

      CI2: duplicate_of = CI5

      CI3: duplicate_of = CI5

      CI4: duplicate_of = CI5

      CI5: Master CI

    • If a master CI becomes a duplicate of a CI within the same duplicate CI set, then the selected duplicate becomes the master CI in the duplicate CI set. The rest of the duplicate CIs in the set are set as duplicates of the new master CI.

      Table 3. Example: Attempt to set a master CI as duplicate of a CI within the duplicate CIs set
      CIs Attempted setting Result (System enforced)

      CI1: duplicate_of = CI4

      CI2: duplicate_of = CI4

      CI3: duplicate_of = CI4

      CI4: Master CI

      CI4: duplicate_of = CI1

      CI1: Master CI

      CI2: duplicate_of = CI1

      CI3: duplicate_of = CI1

      CI4: duplicate_of = CI1

  • You cannot delete a CI that is the master CI of duplicate CIs. To delete a master CI, you must first disassociate that master CI with all of its duplicate CIs. Either delete all duplicate CIs that are associated with that master CI, or remove the reference to that master CI from all duplicate_of attributes in any duplicate CIs that have it.
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