Contention versus utilization
Because each layer has its own set of requirements, this translates into two sets of counters or metrics. Each group has its own metrics.
At the VM layer, we care whether a particular VM is being served well by the platform. Other VMs are irrelevant from the VM owner's point of view. So the key counter here is VM contention. Infrastructure metrics are irrelevant here. Only when we are satisfied that there is no contention can we proceed to check whether the VM is sized correctly or not. Most people check for utilization first because that is what they are used to monitoring in the physical infrastructure. In a virtual environment, we should check for contention first.
At the Infrastructure layer, we care whether it serves everyone well. Make sure that there is no contention for resources among all the VMs in the platform. Only when the infrastructure is clear from contention can we troubleshoot a particular VM. If the infrastructure is having a hard time...
