Install the VMware Tools on all VMs. (VMware Tools is not installed on a VM by default.) VMware Tools is a set of utilities and drivers that improve the performance and management of VMs. It includes the balloon driver that is used for memory reclamation in ESX, the custom BusLogic driver that should be used for VMXNET3 paravirtualized network adapter, which contains drivers for many guest OSs.

The following website provides instructions for installing VMware Tools:

When configuring the VMware Tools options, VMware recommends that you enable (check) the “Notify if upgrade is available” option. If this option is not enabled and an upgrade of VMware Tools becomes available, the vCenter Server will automatically apply the upgrade and (in some cases) automatically reboot the VM’s guest OS. The automatic reboot might not be desirable.