When I'm monitoring a Hyper-V cluster through WMI, the WMI performance provider provides one extra performance data for cluster shared volume instance named "Volume1#1". The original instance "Volume1" is no longer being updated with recent data.
What do these duplicate instances mean? Can there be more and if so, how do I determine which one contains recent data?
It turns out that this occurs when there happen to exist two instances with the same name. In this case, there were two filesystems called Volume1, so Windows renamed the second to Volume1#1. The fact that the first instance was not updated with new data was most likely a coincidence, there probably was no activity on Volume1.
It is not clear what information is used to map the first and second volume to their corresponding instances though, it might even be random.