By default, you cannot add CPU resources to a virtual machine when the virtual machine is turned on. The CPU hot plug option lets you add CPU resources to a running virtual machine.

Before you begin

Required privileges: Virtual Machine > Configuration > Settings

Verify that the virtual machine is running and is configured as follows.

  • Latest version of VMware Tools installed.

  • Guest operating system that supports CPU hot plug.

  • Virtual machine compatibility is ESX/ESXi 4.x or later.

  • Virtual machine is turned off.

About this task

The following conditions apply:

  • For best results, use virtual machines that are compatible with ESXi 5.0 or later.

  • Hot-adding multicore virtual CPUs is supported only with virtual machines that are compatible with ESXi 5.0 or later.

  • Not all guest operating systems support CPU hot add. You can disable these settings if the guest is not supported.

  • To use the CPU hot plug feature with virtual machines that are compatible with ESXi 4.x and later, set the Number of cores per socket to 1.

  • Adding CPU resources to a running virtual machine with CPU hot plug enabled disconnects and reconnects all USB passthrough devices that are connected to that virtual machine.

Procedure

  1. Right-click a virtual machine in the inventory and select Edit Settings.
  2. On the Virtual Hardware tab, expand CPU, and select Enable CPU Hot Add.
  3. Click OK.

Results

You can now add CPUs even if the virtual machine is turned on.