De duplication task is not creaed for same serial number

[testtenentt]

Hi Everyone,

I am currently facing an issue with CMDB duplicate detection for the cmdb_ci_computer table and would appreciate your guidance.

• Identification Rule is configured as follows:

  • Priority 1 → serial_number

  • Priority 2 → name

• Two CIs exist with the same serial number

• Both belong to the same CI class: cmdb_ci_computer

Duplicate Metric Configuration:

• Active = true

• Create Task = true

• Correctness Score Calculation job is running daily

Observation:

For some serial numbers, duplicate remediation tasks are created successfully.

However, for other serial numbers, even though two CIs exist with the same serial number, no duplicate task is created.

I would like to understand:

• Is duplicate task creation dependent on specific CI attributes such as install status or lifecycle state?

• Is there any other functionality or configuration that controls the creation of duplicate remediation tasks?

• Are there any additional checks performed by CMDB Health before generating duplicate tasks?

Could someone please help clarify this behavior?

Thank you in advance for your support.

[sivasankaris]

Hi @testtenentt,

Please check the Health Inclusion Rule, as this rule controls which CIs are eligible for identification and duplicate detection by IRE.

Navigation: All → CI Class Manager → Computer → Identification Rules tab → Inclusion Rule

In this rule, check whether any Install Status or Operational Status conditions are set.
Only CIs that match these conditions will be considered when IRE checks attributes for newly discovered CIs.

From your case, it looks like the decommissioned CIs are not included in the IRE matching process.
Because of this, IRE does not detect them as duplicates, the duplicate_of field remains empty, and no dedup task is created..

Hope this will clear your confusion.. If this works please mark it as helpful and please Accept My Solution...

Best Regards

SIVASANKARI S

[testtenentt]

Thanks for your feedback.
I see in my instance, there is no inclusion rules added.
Is there any checks i need do further, Please provide.
why Duplicate task is not created for CIs.

[fknell]

Hi @testtenentt,

You’re describing a classic CMDB Health / Duplicate Metric behavior that can be confusing at first. The fact that some serial numbers trigger duplicate remediation tasks and others do not, even when two cmdb_ci_computer records have the same serial_number, is usually due to additional checks performed by CMDB Health and IRE, not just the Identification Rule alone.

How to investigate your specific cases

To understand why some serial numbers are not creating tasks:

1. Check discovery_source and duplicate_of 

- For each pair of CIs with the same serial_number, verify:

   - discovery_source  (same / different / empty),

   - duplicate_of  (is one already tagged as duplicate?).

2. Check system properties

- Look at:

   - glide.identification_engine.skip_duplicates 

   - glide.identification_engine.skip_duplicates.threshold 

- If skip_duplicates = true and the count is below the threshold, IRE may be auto‑reconciling instead of creating tasks.

3. Manually create a de‑duplication task if needed

- If you know there are duplicates but no task is created, you can manually create a de‑duplication task and run remediation.

For more details about de-duplication see the following KBA: CMDB Health - Duplicate Metric algorithm 

In your case decommissioned CIs with the same serial_number may not trigger tasks, even if duplicate_of is empty, because the Duplicate Metric focuses on operational records. 

Hope this helps for your further investigation!

[testtenentt]

Thank you for inputs
1.
I see duplicate of is empty.
Data source is same.
2.
glide.identification_engine.skip_duplicates---true
glide.identification_engine.skip_duplicates.threshold--5(value-integer type).