Discovery creating duplicate Windows Server CIs

MichelleS384771
Tera Contributor

4 hours ago

We’re seeing duplicate Windows Server CIs created by ServiceNow Discovery where the newly created CI has an empty Serial Number. These duplicate records appear to be created during Discovery runs and only once per affected server.

Key indicators on the duplicate CI:

  • sys_created_by = mid.xxxx
  • discovery_source = ServiceNow

 

What we observed

  1. Duplicates are on a Windows server class
  2. discovery_source = ServiceNow
  3. Duplicate CI has empty serial number

Identification Rules (Computer / Server inheritance). During the run that created the duplicate CI:

  • Serial number + type → Not matched
  • Name + serial number → Not matched
  • Serial number → Not matched
  • Name (Priority 450) → I believed should match 
  • MAC + Name (Priority 500) → should match 

Yet IRE still created a new CI (empty serial) instead of updating the existing one.

 

1) Why is Discovery returning empty Serial Number for Windows servers?

2) Best practice mitigation?

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1 REPLY 1

fknell
Tera Patron

3 hours ago

Hi @MichelleS384771 ,

Does the error also occur when you manually discover the CI? If so, how do you discover the CIs WMI, ACC-V?

 

If you know the payload, you can simulate the IRE process to identify which identification rules match. I wrote an article on that topic Identification Simulation: Testing IRE Rules and Creating Mock Data  .

 

ServiceNow also offers a Get Well Playbook Hardware CIs without Serial Numbers on that topic, which might be interesting for you since you asked for best practices.  

 

You can remediate this by using deduplication templates as well, but I guess it's worth to identify why the discovery doesn't return the serial after the first scan.

 

Hope this helps!

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