Collecting Usage Metrics
Collecting usage metrics
However, collecting usage metrics may not be an easy task. Installing system management agents on your virtual machines that were designed for the older generation physical servers may artificially skew your results by overburdening the hypervisors with extra CPU and network.
Collecting metrics via agentless may also prove challenging if you are working with several hundred VMs. Creating a matrix of usage compared to capacity you have allocated will give you a pretty good idea of where the efficiency of each of your VMs is.
Immediately, the outliers will be evident. VMs that track well below what they have been allocated during peak hours may be ideal candidates for reduction and their capacity can be recycled. VMs that are over-utilized may benefit from a reallocation of resources. Alternatively, if something may be wrong, a root cause analysis may expose a configuration change from the original template causing the error.
Once armed with an understanding of the utilization range for each VM in their given capacity, a threshold window can easily be crafted. In an ideal world, a VM should not be over-allocated, nor should it be under-allocated or, even worse, left entirely idle consuming precious resources. Typically, a VM should average in the 65 to 80 percent range for Web servers. If your VM is averaging 20 percent, then maybe it's time to rethink your allocation.