Action details- VM resize impact on energy usage and carbon footprint

Turbonomic shows the projected change in energy usage and carbon footprint in the action details for on-prem VM resize actions. You can use these metrics to understand projected impact on energy usage and carbon footprint that is associated with resizing VMs.

Carbon footprint and energy usage action details

In Action Center, when you click the Details button for a VM resize action, the Resource Impact table on the Action Details page includes rows for Energy, Usage and Carbon Footprint, Usage.

  • The Energy, Usage row shows the aggregated energy usage in watt-hours over a 10-minute interval. The Current value is the latest measurement for energy usage. The After Actions value is the projected 10-minute energy usage after all pending actions are executed.

  • The Carbon footprint, Usage row shows the aggregated carbon footprint in grams over a 10-minute interval. The Current value is the latest carbon footprint measurement. The After Actions value is the projected carbon footprint for a 10-minute interval after all pending actions are executed.

For more information about these values, see Carbon Footprint Calculation and Calculation of Energy Consumed by VMs. For more information about how Turbonomic calculates the change in these values due to resize actions, see the next section.

Calculating projected energy usage and carbon footprint for on-prem VM resize Actions

Turbonomic calculates energy usage for each VM on a host, based on two types of host energy:

  • Host overhead energy: Energy that is consumed by non-VM resources, such as hypervisors. This value includes host idle energy, the energy consumed by a host while it is in an idle state, when no processes are actively executing.

    Host overhead energy is attributed to all member VMs based on each VM’s allocated capacity.

  • Host active energy: The energy consumed by the VMs' operating systems and active processes.

    Host active energy is attributed to all member VMs based on each VM’s usage of host CPU.

The calculation can be expressed as follows:

(VM Size / Total Size for all VMs) * Host Overhead Energy for VMs + 
(VM CPU Utilization / Total CPU Utilization for all VMs) * Host Active Energy for VMs 
= VM Energy usage (in Wh)
Note:

Turbonomic rounds the calculated values.

The impact of resize actions on VM energy usage can be understood as a change in the values of VM Size and VM CPU Utilization in the previous equation. As a VM resizes down, its share of the total size and CPU utilization for all VMs on the host also decreases, which in turn decreases the calculated VM Energy usage (in Wh) value.

Similarly, the projected carbon footprint of the VM following a resize action is computed by applying the carbon-energy relationship to the projected energy usage from previous step:
Projected carbon footprint = projected energy * PUE * CI

For more information about the carbon-energy relationship, Power Usage Effectiveness (PUE), and Carbon Intensity (CI), see Carbon Footprint Calculation.

However, the After Actions values for energy usage and carbon footprint that appear on the Action Details page are the projected values after all pending actions are executed, not just resize actions. In some cases, the After Actions values might be greater than the Current values. This comparison does not indicate that overall energy usage increases when the action are executed. Instead, as a result of pending move actions on the same host, this particular VM might represent a larger share of the overall energy usage and carbon footprint after other VMs are moved off the host.