Does anyone know where does the value for this property come from? I mean, where does the agent get this info?
I have seen that for some servers this value is empty, although via remote desktop I have verified that they are actually patched (I was checking all Windows 2003 servers to see if they were all SP1 or SP2).
I was assuming that BL agent ckecks if the SP is in the Applications list (Add or Remove programs), but it doesn’t look so, as on some servers the application is available and still the OS_PATCH_LEVEL value is empty.
So, summarizing: for some servers the OS_PATCH_LEVEL property is empty, although connecting to the server (remote desktop) and checking under Control Panel / System, those servers are actually patched to SP1.
I use the OS_PATCH_LEVEL property and not experienced what you describe. In general I find it to be a reliable indicator of SP level. This is basic, but I'll ask just in case...
Has update properties been run against the target after the service pack was applied?