The OS Cluster Layer
The tests mapped to this layer measure the health and performance of the Failover Cluster Service (if enabled) on the Windows server that is hosting the monitored Hyper-V server. Additionally, the test also monitors I/O traffic to each Cluster Shared Volume (CSV) the Hyper-V cluster supports, and points you to overloaded CSVs. The CSV Cache is also monitored and administrators proactively alerted to ineffective cache usage .
The tests mapped to the OS Cluster layer run only in the agent-based mode. This is why, you need to install an eG agent on at least one node in the cluster to enable these tests to report cluster-level metrics. For best results however, it is recommended that you install an eG agent on each node in the cluster; this way, even if one node goes down due to any reason, cluster health can continue to be monitored using the agents on the other nodes.