How to Change the Number of Virtual CPUs in the vSphere Web Client

You can configure a virtual machine that runs on an ESXi host to have up to 32 virtual CPUs.

Virtual CPU hot add is supported for virtual machines with multicore CPU support and running on hardware version 8 or later.

When the virtual machine is powered on, and CPU hot adds is enabled, you can hot add virtual CPUs to the running virtual machine.

You can only add multiples of the number of cores per socket.

 

 

Prerequisites

 

  • If CPU hot add is not enabled, power off the virtual machine before adding CPUs.
  • If CPU hot remove is not enabled, power off the virtual machine before removing CPUs.
  • To hot add multicore CPUs, verify that the virtual machine has hardware version 8.

 

Required privilege: Virtual Machine.Configuration.Change CPU Count on the virtual machine

 

Procedure

 

  1. Select a virtual machine.
  2. In the VM Hardware panel, click Edit Settings.
  3. Click Virtual Hardware.
  4. Expand the CPU options, and select the number of cores for the virtual machine from the Cores dropdown menu.
  5. Select the number of cores per socket from the Cores Per Socket drop-down menu.
  6. Click OK

 


 

The vSphere Web Client computes the total number of virtual sockets from the number of cores and cores per socket that you select.

 

Below is relationship between vSphere client and vSphere Webclient

 


 

 

Example: Adding Multicore CPU Resources to a Virtual Machine

 

You might have the following existing CPU resources, which you configured for the virtual machine

while you were creating it, or after you created it and it was in a powered off state.

 

CPU Resource Settings

Existing Value

Number of virtual sockets

2

Number of cores per socket

2

Total number of cores

4

 

 

With CPU hot plug enabled and the virtual machine running, you can select the number of sockets to add from the Number of virtual sockets drop-down menu.

The Number of cores per socket drop-down menu is unavailable and retains a value of 2.

If you select 3 virtual sockets, you are adding 1 socket with 2 cores so that the virtual machine has 6 virtual CPUs

 

 

CPU Resource Settings

Existing Value

Hot-Plug Value

Number of virtual sockets

2

3

Number of cores per socket

2

2

Total number of cores

4

6

 

In other words you cannot change cores but only socket


 

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