Memory hot add lets you add memory resources for a virtual machine while that virtual machine is powered on.

Enabling memory hot add produces some memory overhead on the ESXi host for the virtual machine.
Note: If the ESXi host is of version 7.0 Update 2 and earlier, hot-adding memory to a virtual machine with NVIDIA vGPU requires that the ESXi host has a free vGPU slot. Starting with vSphere 7.0 Update 3, the source host does not require to have a free vGPU slot.

Prerequisites

  • Power off the virtual machine.
  • Verify that the virtual machine has a guest operating system that supports memory hot add functionality.
  • Verify that the virtual machine compatibility is ESXi 4.x and later.
  • Verify that VMware Tools is installed.

Procedure

  1. Right-click a virtual machine in the inventory and select Edit Settings.
  2. On the Virtual Hardware tab, expand Memory, and select Enable to enable adding memory to the virtual machine while it is powered on.
  3. Click OK.

Results

You can now add memory to a virtual machine, even if the virtual machine is turned on.