6.0

Managing Hardware for an ESXi Host by Using the VMware Host Client
When you log in to an ESXi host by using the VMware Host Client, you can manage PCI devices and
congure power management seings.
Host Power Management Policies
You can apply several power management features in ESXi that the host hardware provides to adjust the
balance between performance and power. You can control how ESXi uses these features by selecting a power
management policy.
Selecting a high-performance policy provides more absolute performance, but at lower eciency and
performance per wa. Low-power policies provide less absolute performance, but at higher eciency.
ESXi provides ve power management policies. If the host does not support power management, or if the
BIOS seings specify that the host operating system is not allowed to manage power, only the Not
Supported policy is available.
You can select a policy for the host that you manage by using the VMware Host Client. If you do not select a
policy, ESXi uses Balanced by default.
Table 2‑1. CPU Power Management Policies
Power Management Policy Description
High Performance Do not use any power management features.
Balanced (Default) Reduce energy consumption with minimal performance
compromise
Low Power Reduce energy consumption at the risk of lower
performance
Custom User-dened power management policy. Advanced
conguration becomes available.
When a CPU runs at lower frequency, it can also run at lower voltage, which saves power. This type of
power management is typically called Dynamic Voltage and Frequency Scaling (DVFS). ESXi aempts to
adjust CPU frequencies so that virtual machine performance is not aected.
When a CPU is idle, ESXi can apply deep halt states, also known as C-states. The deeper the C-state, the less
power the CPU uses, but it also takes longer for the CPU to start running again. When a CPU becomes idle,
ESXi applies an algorithm to predict the idle state duration and chooses an appropriate C-state to enter. In
power management policies that do not use deep C-states, ESXi uses only the shallowest halt state for idle
CPUs, C1.
Change Power Management Policies in the VMware Host Client
Change the power management policies of the host that you are managing to control the energy
consumption of your host.
Procedure
1 Click Manage in the VMware Host Client inventory and click Hardware.
2 Click Power Management and click Change policy.
The available power management policies are displayed.
3 Select the radio buon next to the policy that you want to apply.
4 Click OK.
Chapter 2 Host Management with the VMware Host Client
VMware, Inc. 13