The easiest way to determine whether the balloon driver for a VM is not running is through esxtop.
- Open esxtop or resxtop for the host.
- Switch to the Memory screen, and add the MCTL fields.
- If the MCTL? field contains N for any VM, then the balloon driver is not running in that VM.
Note: The balloon driver is an important part of the proper operation of the ESX memory management system. The balloon driver should never be deliberately disabled in a VM. This may cause unintended performance problems (e.g. swapping), and makes tracking down memory-related problems difficult. vSphere provides other mechanisms, such as memory reservations, for controlling the amount of memory available to a VM.
Install VMware Tools and make sure the Memory Control Driver is installed.