Influence of power management on VDI performance
Tuning your image can have a huge impact on the performance of your environment. Tools like VMware OSOT or the Citrix Optimizer can help you with this. While most of the individual settings within your image have a small impact on the performance there is one setting outside of your image which has a big impact. The power management of your hypervisor. This setting is a bit hidden and easy to forget. Setting it correctly in your BIOS isn’t always enough.
Where you can set the power management in the BIOS is different for every vendor. The naming for the option is also different per vendor. Most vendors allow you to set four different flavors of power management, going from low, balanced, to high and as additional flavor: OS controlled power management. Important to know is that OS controlled power management means the BIOS allows to be overruled by the OS. It can mean you have to set the power management in the hypervisor itself.
For example in the vCenter you can set the power management under the Configure tab of the hosts itself. To make it more difficult for you; VMware created in the vCenter two tabs in the config of your hosts that are called power management. The power management tab underneath hardware should allow you to set an active policy. Make sure it is set to high performance!
With so many options it is easy to misconfigure the setting but the impact can be huge. My colleague Mark Plettenberg executed several tests in the VDI Like a Pro labs to prove the impact. With fully automated tests and over ten test runs the average impact on the baseline was 64%. Sixty four percent of free user experience improvement.
“Faulty power management is the most common but easiest to fix VDI mistake. Configuring this properly can save your users a lot of energy as user experience will increase”
Recognizing the faulty power management after a Login VSI test is relatively easy. The Login VSI VSImax graphs are build based on linear user load. This means our graphs should show a nice linear line upwards like in the graph underneath.
When the performance (y-axis) of your system is better with a higher load (x-axis) something is wrong. After a Login VSI test you can see this in the Login VSI VSImax graphs. It will start to show waves. This should be an alarm trigger to check your power management!
Faulty power settings
So, make sure you check, set and test the configuration. Mistakes in the power management are easy to make but also easy to discover. Test and verify if you have set the correct setting can be the difference between a good performing VDI and unhappy end-users.
For more information on power and performance, see these other helpful blogs:
- Helge Klein - The Effects of HP’s Power Profile on vCPU Performance
- VMware VROOM! Blog - Power Management and Performance in VMware vSphere 5.1 and 5.5