question Service Discovery not working in CMDB forum

Service Discovery not working

Asmita20 — Mon, 13 Apr 2026 12:26:10 GMT

I created a service discovery using a service attribute and applied a filter on the serial number, but it is not working. Please suggest what I should do.

Re: Service Discovery not working

KanteS — Mon, 13 Apr 2026 16:01:42 GMT

Hi,

If the serial number filter in Service Discovery is not working, the issue is usually with data retrieval or identification logic.

Things to check:

Verify Serial Number Retrieval
Check the ECC Queue and confirm the serial number is actually being captured. If it’s not present, the filter will never work.
Check Identification Rules (IRE)
The serial number must exactly match what exists in CMDB (no extra spaces or case differences).
Also ensure the identification rule for that CI class includes serial number.
Validate Pattern / Attribute Mapping
Run Discovery in Debug mode and confirm the serial number is being mapped correctly (e.g., $serial_number).
Permissions / Access
Make sure credentials used by MID Server have access to fetch hardware details (WMI/SNMP/Linux commands like dmidecode).

If the serial number is not coming from the source or not mapped correctly, the filter will not work.

If this helped, please give a like and mark it as the solution.

Re: Service Discovery not working

Tanushree Maiti — Mon, 13 Apr 2026 16:40:23 GMT

Hi @Asmita20

1) Check your IRE rule:

Go to CI Class Manager -> <your Class> -> Identification Rules.

If "Serial Number" is not a high-priority identifier, the system might be matching on Name instead,

might bypass your filter logic

2) Run the discovery in Debug Mode to see exactly what value is being returned in the Identification phase.

Open identification section and click on patter debug mode. Provide the IP address and mid server and start.

From there do step by step debugging in which step serial number data is receive and in which step serial number is mapped to CMDB table (Refer: https://www.servicenow.com/community/itom-forum/missing-serial-numbers-for-windows-servers-and-network-devices/m-p/3193352#:~:text=open%20identification%20section%20and%20click,Hi%20Rahim%2C)

3) Ensure Mid server is up and running fine

4) you have correct credential with proper permission