The MP however only discovered one of these six Hyper-V servers. And these servers are exactly the same: hardware, OS, OpsMgr Agent, QFE’s, W2K08 related update for OpsMgr. Also the network- and firewall settings were exactly the same.
The eventlogs of these servers showed no problems what so ever. All MPs were neatly downloaded to these servers and all other discoveries (like W2K08 Core Installation) ran fine. Just the Hyper-V MP got this nagging issue.
Stopped the health service on these servers, deleted the HealthState folder but all to no avail. Rebooted the server during midnight but still no discovery of Hyper-V.
Finally I removed the OpsMgr Agent, reinstalled it with all related QFE’s and W2K08 related update for OpsMgr.
And guess what: The servers are now being properly disovered ad Hyper-V servers.
I am puzzled since all other MPs ran like clockwork and no errors (eventlogs, OpsMgr Console) showed up.
But hey, it is working now.