How to change Service Population Method for Service Mapping CSDM

[peggyl]

Hi, 

We have a list of existing Application Service CIs in the CMDB which were created using CSDM UI form.  During the time of creation (which could be many months/years ago) the service mapping method we used was Manual Service Population Method. 
Due to cloud modernisation, we have now moved to cloud discovery.  

We would like to change the Service Population Method of the EXISTING Application Service CIs and use "Tagged based" Service Mapping. 

However, when I go to the Application Service CI record to try and change the service population method to Tagged based, I'm unable to do so as it is not one of a selection I can make.  (see attached screen shot)

Any insights as to how I can change the service mapping method for our existing Application Service CI, would be greatly appreciated.  Thank you.

[Robert Campbell]

From the list view, search for the services you want to "change". Be sure to have class listed as a column. Change the class to "Application Service". 

Now when you open the record in CSDM view you can add new methods.

[AJ-TechTrek]

Hi @peggyl ,

I see exactly what you mean from your screenshot.
You’re trying to switch existing Application Service CIs (created manually via CSDM form) to use Tag-based Service Mapping (Cloud Discovery population), but the option doesn’t show in the Service Population Method list.

Why you don’t see “Tag-based” as an option
* In ServiceNow, the Service Population Method field (cmdb_ci_service.service_population_method) only shows methods that are valid at the time of creation of the Application Service.
* The “Tag-based” option isn’t directly available in that dropdown for existing Application Services created manually.

* Tag-based Service Mapping actually relies on Service Mapping (SM) patterns + cloud discovery tags to dynamically populate the service, not a direct manual switch in the form.

Best Practice Approach to Move from Manual → Tag-Based

You cannot simply flip the dropdown on an existing Application Service. Instead, you have 2 supported approaches:

 Re-create the Application Services via Tag-based Service Mapping

1. Use Service Mapping > Services > New and choose Tag-based as the population method.
2. Configure the cloud tags (from AWS, Azure, GCP, etc.) in the Tag-based service mapping rules.
3. Service Mapping will automatically discover and populate the service based on tags.
4. Retire/archive the old manually created Application Services (or relate them to new ones if you need historical continuity).

This is the recommended approach because it ensures the CMDB follows ServiceNow best practices and avoids data corruption.

Please appreciate the efforts of community contributors by marking appropriate response as Mark my Answer Helpful or Accept Solution this may help other community users to follow correct solution in future.
 

Thank You
AJ - TechTrek with AJ - ITOM Trainer
LinkedIn:- https://www.linkedin.com/in/ajay-kumar-66a91385/
YouTube:- https://www.youtube.com/@learnitomwithaj
Topmate:- https://topmate.io/aj_techtrekwithaj (Connect for 1-1 Session)
ServiceNow Community MVP 2025