If you demote a Domain Controller, SCOM will generate a lot of alerts. By design, there is no automatically undiscovery for the Rules and Monitores for the Active Directory Roles.
Solution 1
This solution will remove all disabled Class instances from an existing object. it will not change any other properties of the object.
- Open the Operations Management Shell
- type in this command:
Remove-SCOMDisabledClassInstance -ComputerName <Demoted Server>
- Stop the System Center Management service
- Delete the folder C:\Program Files\System Center Operations Manager\Agent\Health Service State
- Start the System Center Management service
Solution 2
This solution will clear only the agent cache. Sometime this will be sufficient, if the server discovery / undiscovery was already done well:
- Stop the System Center Management service
- Delete the folder C:\Program Files\System Center Operations Manager\Agent\Health Service State
- Start the System Center Management service
Solution 3
This solution will remove the entire object and then recreate the object with it’s discovery. The new object wouldn’t be discovered as Domain Controller. The new object will have an new guid and any overwrites to the old object will be lost.
- Stop the System Center Management service
- Delete the folder C:\Program Files\System Center Operations Manager\Agent\Health Service State
- Open the SCOM console
- go to Administration → Agent Managed
- delete the affected server
- use the Discovery Wizard to redeploy the agent to the affected server
- The System Center Management service will automatically restarted