CPU Hot Plug Enable and Disable options are grayed out for virtual machines

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

Symptoms:
In the vSphere Client inventory, the Enable and Disable buttons are grayed out for CPU Hot Plug for virtual machines, even when the virtual machines are powered off.

Environment

VMware vCenter Server 4.1.x
VMware vSphere ESXi 5.5
VMware vSphere ESXi 5.1
VMware vSphere ESXi 6.0
VMware vCenter Server 6.0.x

Cause

This issue occurs because not all Linux kernels and Windows operating systems support CPU hot plug features.

Resolution

CPU Hot Plug functionality is dependent upon whether the guest OS supports CPU hot add and CPU hot remove.

Guest operating system support for CPU Hot Plug

• Linux: Newer Linux kernels have support for CPU hot add. To verify this, check the documentation for your Linux distribution in the documentation directory of the distribution source code. The documentation contains directions for special boot time switches related to CPU Hot Plug. CPU hot remove is not supported at this time.
  
  
• Windows: Windows Server 2012 (Standard and Datacenter Edition) and Windows Server 2008 Datacenter Edition support CPU hot add, but not CPU hot remove.

Note: Windows Server 2008 Standard and Enterprise Editions do not support CPU hot add.

Additional Information

If you are experiencing CPU hot add issues with Windows 8 or Windows Server 2012, see A Windows 8 or Windows Server 2012 virtual machine fails to recognize hot-added virtual CPUs (2050800).

For more information about Guest OS compatibility, see the VMware Guest OS Compatibility Guide.

A Windows 8 or Windows Server 2012 virtual machine fails to recognize hot-added virtual CPUs
仮想マシンで CPU ホットプラグの有効化および無効化オプションが灰色表示される
虚拟机的 CPU 热插拔启用和禁用选项呈灰色