Random VMs provisioned with more than 2 vCPUs, but only 2 CPUs are online within the Guest operating system.

Products

• VMware vSphere ESXi

Issue/Introduction

The number of vCPUs and cores per socket are correctly configured, and CPU HotAdd is enabled.

Please refer : Virtual machine CPU and socket configuration

Environment

VMware vSphere 7.x
VMware vSphere 8.x

Cause

In cases where CPU cores appear offline within a VM, it is often related to issues within the Guest Operating System.

Resolution

Investigate the Guest OS by reviewing the OS logs/events/settings to identify any underlying causes.  Also check the last reboot time to determine whether the CPUs were online or offline prior to the restart.