This documentation supports the 20.02 version of BMC CMDB.

To view an earlier version, select the version from the Product version menu.

Best Practices for the Common Data Model

As a configuration manager, how you work with the Common Data Model (CDM) can have a huge business impact on your organization and it is good to know the following information before you proceed.

  • It is best not to begin working in the CDM by extending the CDM to customize the classes suitable to your environment. 
  • You should first understand what exists in the CDM, look for suitable classes from what is provided out-of-the-box. 
  • Only if you do not find suitable constructs, then extend the CDM.


    You should not create overlays if you need to extend the CDM. BMC CMDB does not support overlays. Ideally, all the modifications on the CDM forms must be done using the Class Manager.

  • You should map your CIs in the CDM depending on the classes required by the data source provider.  

  • It is better plan your CDM and have a map to load CDM. Plan in advance how you will leverage the CDM. You can use the data model to map objects to BMC recommended mappings. For example, map a desktop to computer systems and not to an equipment. 

  • Use the CDM to map important equipment, CIs, machinery, building or a location to the right mappings in CDM.  

Here are few examples on how to map CIs or equipment in CDM

  • If you have a coffee machine that is important in your business you map it to the equipment class, you are successful.
  • Sometimes Air Conditioners are a critical piece of equipment which need to be tracked. If an Air Conditioner goes down the data center gets affected. In such case map Air Conditioner to an equipment class and define a relationship. 
    Building --> Floor–> Data Center--> AC (You can map these relationships in Atrium Explorer).
  • For modelling a cluster, use a cluster class set the relationship to the machinery, the machinery is connected to the application. 

Remember, that the CDM is a dynamically growing model. You should plan your mappings, put information in CDM and start using it. Treat the CDM like a template, and populate it as per your requirement. It is not essential to fill out all the classes provided out of the box in CDM. 

 The BMC CMDB is able to cope with multiple relationship types such as 1 to 1 relationship, 1 to many relationship , many to many relationship, and many to 1 relationship. 

Expert Speak

Key characteristics of Common Data Model are:

  • Provides a standard for modeling configuration data
  • Eliminates the confusion and interaction problems between applications/solutions that have different data layouts and interpretations
  • Use the elements of the CDM that are required for your business and your environment
  • It is likely that not all classes and attributes provided in CDM will be used in your environment.
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