Hypervisor Memory Details Test

If one/more desktops on a VirtualBox are responding slowly to user requests, and the "inside view" of the desktops does not reveal anything untoward, then, you may want to focus on the measures reported by this test as they can indicate whether/not there is any contention for memory resources at the host-level. This is because, if the VirtualBox host has insufficient memory, it will adversely impact the memory allocations to the desktops on that VirtualBox, and consequently stall desktop operations. 

This test closely monitors how the VirtualBox host and hypervisor use the physical memory resources, and warns administrators of potential memory crunches (if any).

Target of the test : An Oracle VirtualBox

Agent deploying the test : A remote agent

Outputs of the test : One set of results for the Oracle VirtualBox being monitored.

Configurable parameters for the test
Parameter Description

Test period

How often should the test be executed


The host for which the test is to be configured.


The port number at which the specified Host listens to.

Oracle Hypervisor

Specify the name of the user who has the right to access the VirtualBox via SSH.

Oracle Hypervisor Password

Provide the password of the oracle hypervisor user.

Confirm Password

Confirm the password by retyping it here.


This test executes certain privileged VDA (Virtual Desktop Access) commands to pull out the desired metrics from the VirtualBox. To enable the test to run these commands, you first need to install a sudo package on the VirtualBox host. The procedure for installing this package is detailed in Pre-requisites for Auto-Discovering VMs and Obtaining their Outside View. Once the package is installed, you need to specify the full path to the install directory of the sudo package in the Sudocmd text box.

Measurements made by the test
Measurement Description Measurement Unit Interpretation

Total physical memory

Indicates the total amount of physical memory installed on Oracle VirtualBox.



Used physical memory

Indicates the amount of physical memory currently used by the VirtualBox.


Ideally, the value of this measure should be low.

Free physical memory

Indicates the amount of unused physical memory on the VirtualBox.


Ideally, the value of this measure should be high. A consistent decrease in the value of this measure is indicative of a steady memory erosion, which if left unattended, can significantly impact desktop functioning.

Physical memory utilization

Indicates the percentage of physical memory utilized by the VirtualBox.


A low value is desired for this measure. If the value of this measure grows very close to 100%, it indicates that the VirtualBox will soon run out of physical memory resources. Such an occurrence can prove to be detrimental to not only the health of the VirtualBox, but also the desktops operating on it.

Used hypervisor Physical memory

Indicates the total amount of physical memory currently being used by the hypervisor.


If the Physical memory utilization measure reports a very high value, take a look at the value reported by this measure to determine whether the processes executing on the hypervisor are consuming too much physical memory.

Free hypervisor physical memory

Indicates the total amount of physical memory free inside the hypervisor.


A high value is desired for this measure. If the measure reports a very low value, it indicates that the hypervisor does not have adequate memory for its operations.

Ballooned hypervisor physical memory

Indicates the total physical memory ballooned by the hypervisor.


Normally, to change the amount of memory allocated to a virtual machine, one has to shut down the virtual machine entirely and modify its settings. With memory ballooning, memory that was allocated for a virtual machine can be given to another virtual machine without having to shut the machine down.

When memory ballooning is requested, the VirtualBox allocates physical memory from the guest operating system on the kernel level and locks this memory down in the guest. This ensures that the guest will not use that memory any longer; no guest applications can allocate it, and the guest kernel will not use it either. VirtualBox can then re-use this memory and give it to another virtual machine.

The memory made available through the ballooning mechanism is only available for re-use by VirtualBox. It is not returned as free memory to the host. Requesting balloon memory from a running guest will therefore not increase the amount of free, unallocated memory on the host.

Effectively, memory ballooning is therefore a memory overcommitment mechanism for multiple virtual machines while they are running. This can be useful to temporarily start another machine, or in more complicated environments, for sophisticated memory management of many virtual machines that may be running in parallel depending on how memory is used by the guests.

Shared memory

Indicates the total physical memory shared between the VMs.


Shared Memory is a feature that enables more desktops to run on Oracle VDI Hypervisor hosts. By specifying an amount of memory to be shared between desktops, the Oracle VDI hypervisor host's memory can be automatically redistributed between desktops as required.

The memory sharing percentage is the amount of memory that can be used for other desktops if a desktop does not require the full amount of memory for itself. For instance, if the desktop memory size is 1 GB and memory sharing is set to 40%, the desktop will initially have around 600 MB of real memory. The other 400 MB will be made available to the desktop on demand.