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Save energy without reducing VM performance in your VMware vSphere cluster

Over the last couple of decades energy consumption went up massively in every data center and while the costs were always high, they were manageable. For some time you can see more and more companies that started “Green Initiatives” to reduce energy waste and the sudden energy crisis accelerates the need for change,

One of the most common energy-saving practices is to turn off servers and other devices when they are not in use. However, turning off these devices can often lead to performance degradation and even data loss.

A VMware vSphere cluster is a group of physical or virtualized servers that work together as if they were one. When you’re running a VMware vSphere cluster, it’s important to ensure that your ESXi host has been configured properly for energy savings without sacrificing performance.

Small optimization in a larger setup can already save real money within a week:

You should consider looking into:

  • Power management settings on ESXi hosts
  • Storage power management

We are going to focus on the Power management of the ESXi hosts in this blog.

VMware vSphere has a feature called DPM (Distributed Power Management) that allows migrating virtual machines to a fewer amount of ESXi hosts in a cluster with the goal of freeing up some ESXi hosts completely. These hosts that run no VM anymore can be switched to standby mode reducing the power consumption massively. Whenever the resources within the cluster are not sufficient anymore, the standby hosts are automatically powered on again using wake on LAN or the KVM functionality of the server.

The standby hosts must be configured in such a way that they can take over the role of the host that just went off-line. If a host goes down during migration and is not capable to take over, DPM will halt the migration process.

You can find out more about the DPM configuration here:

or the whole tech paper:

To have a good understanding what power consumption can be reduced without annoying users with slowed-down application response times, Opvizor Metrics & Logs supports you with several dashboards. That can help you find the best ways to optimize energy use and your performance.

most important dashboards to use while reducing power consumption

The dashboard dedicated to showing the achieved reduction in power consumption is called VMware DPM Host Power Consumption. You can define the price per kWh and the reference period to see the detailed changes in your ESXi energy use.

Hint: longer reference periods can only be used when Metrics & Logs is already collecting data for that time range

To monitor the overall performance over time, Opvizor Metrics & Logs has many more dashboards to offer.

Starter Dashboards

and dedicated Performance Dashboards:

Start your free trial and save energy costs