Station Mapping : Virtual Machine (VDI) Desktop

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Copyright © 2016 Userful Corporation. All rights reserved.
(Updated 2016.02.19)

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Userful's Virtual Desktop Infrastructure (VDI) solution is a feature that makes it possible to map full-screen Virtual Desktop sessions to stations.

"Station Mapping" lets a system administrator configure what type of Virtual Desktop session to launch on each station. With a "mapped" session, end users no longer need to login to the native linux desktop to start the virtual desktop session. Once the system administrator has mapped a Virtual Machine (VM) session to a station, a "clone" of the master VM will automatically launch as a full-screen session on that station.

A key advantage Userful's design is that cloning is automatic and quick; clones are copied from "known good" virtual machine master images known as golden masters.

This document includes information about the Virtual Machine session container.

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Station Mapping: Creating a Virtual Machine Session Container

Station Mapping allows you to bind a specific station to a Virtual Machine clone.

  1. The first step is to create a Virtual Machine session container. To do so, click on "New Session Container" button. Select the container type as "Virtual Machine" and give a name.

  2. UCC Station Mapping VM.png
  3. Choose a master VM from the drop down menu.
    • Master VMs must be configured through "Virtual Machines" tab; in order to appear in this list. Please see Creating a VM Master Image for more details.
    • When stations are mapped to this session, "clones" of the master VM will be created automatically.
  4. Choose the audio controller from the drop-down list based on the Guest OS.
  5. Choose CPU cores from the drop-down
  6. Select the amount of RAM allocated for each VM clone
  7. Choose whether the clone(s) should be writable or locked by either clicking in the radio button next to "Retain VDI changes" or "Discard VDI changes", respectively.
    • Retain VDI changes after each session (unlocked): Clones do not revert back to the previous state when they are rebooted. In other words, changes to the cloned images persist across reboots.
    • Discard VDI changes after each session (locked): Clones automatically revert to the Master VM state (when the clone was last created or last re-synchronized) when the VM (or the host) is rebooted. This is best for kiosk mode.

Map Stations to Virtual Machine Session Container

UCC Map VMStation.png

Once session is created, stations can be "mapped" or assigned to the session by simply dragging-and-dropping the station icons.

To change the session configuration (e.g.,to enable Auto-Reset state), click on the session container name to open the "Edit Session Container" window.
Note: Changes will not take effect until the "Apply" button is clicked.

Please Note: It is recommended not to map host PC to VM session container.

Licensing is Your Responsibility

Please Note: You are responsible for complying with all operating system and application vendors’ license agreements when you clone a virtual machine or make it available for multiple users.

Considerations When Mapping Virtual Machines

  • Ensure that sufficient system resources, especially RAM, is available for all cloned station maps. For optimal setup we generally recommend that administrators should double the minimum RAM to allow for extra capacity (due to failover or growth) or if you anticipate that users may perform memory intensive tasks on the host PC.
    • For example, if the master VM has been allocated 512 MB, and there are 15 stations, the system must have at least 8GB RAM available. Remember that the host PC requires between 2 -3 GB of RAM itself, and that RAM requirements increase with greater numbers of stations.
  • Userful recommends Quad Core Processor for the host PC.
  • The BIOS of the host PC must be configured to enable the hardware virtualization CPU setting.
  • Though not required, performance will be better with a solid state drive (SDD). In particular, it is recommended to store the VM images on SSD.
  • If cloned VMs are to be bound to an Active Directory domain:
    • The Master VM must not be bound to an Active Directory domain prior to cloning, and
    • "Writable" clones must be used. The reason is that (for security purposes) Windows performs automatic machine password changing at regular intervals. You can disable this automatic password changing according a Microsoft KB article:
  • All Master VM image(s) should be created and stored under the same user account, "administrator" (or any other user who will own the VM images).
  • If you access the internet through a proxy, it is important to configure your golden master image with the correct proxy settings.

Re-synchronizing Virtual Machine Clones

When a Master VM is mapped to stations, a "clone" is created for each mapped station. Both the cloned VMs and the original golden master VM can be viewed and managed within the Oracle VM VirtualBox Manager ( Applications > System Tools > Oracle VM VirtualBox).


The image to the right is an example of how Master, Unlocked Clones, and Locked (or Read-only) Clones appear in the VirtualBox Manager window.

To adjust the master image settings, simply highlight the image in the list, then click on "Settings".

Changes within a virtualized operating system (for example, installing new applications) are made by highlighting the master image, then click on "Start". The guest OS will boot inside a VM window; make any change necessary then shut down the VM.

Please Note: The changes made to the master VM image will not automatically propagate to the clones of that image.

If you have changed a master VM and you wish to apply those changes to all the clones (that is, to all stations that have been mapped to run a VM based off that master image), Click Resyn Clone button under Control Center > Virtual Machines. The clones will automatically be re-created.

Similarly, if you have changed the RAM/Core settings of an exisiting VM under "Edit Session Container" window, the changes will not take effect until the Guest OS does a full shutdown.


If your VMs are sluggish and unresponsive, it may be that you have not allocated enough RAM to the VM. It is possible to change the memory allocation for a VM that has already been installed. Some things to remember:

  • Any changes to the configuration of the VM should be made to the golden master image. Then any clones will need to be resynchronized in order for the changes to be seen in the VM clones.
  • Be sure that increasing the RAM allocated to VMs does not exceed the capacity of your host system. See "Considerations When Using Virtual Machines", above.

If anything bad or unexpected happens during the installation process, or with normal usage, you can reset either individual stations, or the entire Control Center/Station Mapping interface. Here are some userful tips:

  1. Force a station to reload its Station Mapping configuration.
    • If a station is not being mapped correctly, press Ctrl+Alt+Backspace to force it to restart.
  2. Recreate the Station Mapping Clone.
    • If Ctrl+Alt+Backspace does not work, you can try to recreate the clone itself.
    1. Power-off the faulty zero-client device.
    2. As the user who owns the VMs, Logon onto the host.
    3. Launch VirtualBox.
      1. Manually delete the faulty numbered VM clones named "<VM> Clone ##" (Hint: It probably has the VirtualBox Status "Aborted".)
    4. Power-on the faulty zero-client device.
    • When the station powers back on, the Cloned VM will be re-created from the master VM.
  3. Recreate the master VM.
    1. As the user who owns the VMs, Logon onto the host PC.
    2. Launch Control Center.
    3. Navigate to Virtual Machines tab.
    4. Delete the master VM by clicking "Delete VM" button under Master Virtual Machines Summary.
    5. Recreate the master VM by clicking "Import VM image" button under VM Images in shared-files folder.
    6. Once all the stations power back on, the system will begin recloning VMs from the re-created master VM.
  4. Recreate entire VirtualBox environment.
    1. Power-off all zero-client devices assigned as a Virtual Machine
    2. As the user who owns the VMs, Logon onto the host PC.
    3. Delete the following paths:
      • /home/user/.config/VirtualBox
      • /home/user/VirtualBox VMs/
    4. Recreate the master VM as mentioned before.
    5. Boot the new master VM at least once in VirtualBox, to validate if its ready to be cloned.
    6. Power-on the zero-client devices.
    7. Once all the stations power back on, the system will begin recloning VMs from the re-created master VM.
  5. Reset the Station Mapping database.
    1. Launch the Control Center.
      1. Go to Help and Support.
      2. Reset Userful Multiplatform.
      3. Click Apply.
    2. Reboot the host PC.
    3. Launch the Control Center.
      1. Go to Station Mapping.
      2. Create a new Virtual Machine session container.
      3. Assign stations to the newly created session.
      4. Click Apply.