Reimaged Computer impact on the CMDB with SCCM

[Abdellah TAHRI]

For ServieNow consultants working on the CMDB / CSDM area , having some IT infrastructure knowledge can help to debug CMDB issues .

From time to time, a computer may need to be reimaged , this means that the computer will be redeployed as if it was a new machine . The most common reason to reimage is to repair rapidly after the equipment failure (Virus infection for example) , because it may require much effort and time to analyze and repair , so reimaging the computer will bring it back into proper working order .

Let’s see how this operation can impact the CMDB and specially IRE rules with the use of a scanning tool like SCCM .

When a new instance of a CI is discovered by SCCM, an entry with a new ResourceID is generated in the SCCM database.

When the same computer is reimaged, it will create a new line and a new ResourceID, and the previous one is getting deactivated.

As a result, when running the SCCM import, the old ResourceID will not appear anymore, and we will only get the new ones.

We can see this behaviour is being reflected in ServiceNow in the import table (we only get the last ResourceID of the computer) and sys_object_source (previous ResourceID is not being updated, and the new one is being created) .

What should happen is that the IRE should identify that the new ResourceID is the same computer as the previous ResourceID and update the CI , this will avoid the creation of duplicates .

Work with the infrastructure teams to understand their operations that may impact the CMDB .