There appears to be an issue when trying to discover certain SQL 2008 instances with SCOM. Which is related to MOF data not being registered in the WMI repository correctly when SQL is installed.
The error that you will see in your Operations Manager event log is:
DiscoverSQL2008DBEngineDiscovery.vbs : The Query ‘select * from SqlService where SQLServiceType =’1” did not return any valid instances. Please check to see if this is a valid WMI Query.. Invalid class
I’ve had success with the below solution:
From an elevated command prompt, browse to the folder “C:\Program Files (x86)\Microsoft SQL Server\100\Shared”
Run mofcomp sqlmgmproviderxpsp2up.mof
Restart your SCOM Agent on the server.