Starting TurboVNC on Casper nodes

Procedures overview | Using TurboVNC

To run advanced visualization applications remotely on the Casper cluster, use TurboVNC software and the procedures described below.

The documentation applies to running two types of visualization applications.

  1. Applications that use OpenGL to display advanced, 3D graphics on your local machine. These include VAPOR, VisIt*, ParaView*, and Vis5D.
  2. Applications that use X11 forwarding rather than OpenGL.

You can run X11 data analysis packages on the GPU-accelerated Casper nodes without using TurboVNC. However, TurboVNC can provide better display performance than the X11 protocol if you are connecting from a site with low bandwidth or high latency.

Procedures overview

To use TurboVNC, you will need to do the following as described in detail in the next section.

Using TurboVNC

To begin, log in on Casper or Cheyenne.

Start the TurboVNC server

Start the TurboVNC server by running the vncserver_submit command as shown, using the -a option to specify the project code to charge. (That option is not needed if you have set your DAV_PROJECT environment variable to the necessary project code.)

vncserver_submit -o +C "casper&x11" -a project_code

This starts a job on the Casper cluster with a wall-clock time of 4 hours. The default screen geometry is 1024x768. (Run vncserver_submit -h for a list of supported options.) You will be placed into a GNOME 3 desktop by default. Alternatively, you can use the KDE desktop by specifying the option -d kde.

You can run the same command later to retrieve tunnel information about the server session that you have left running. You can start an additional server session by adding -s and a session name, as in -s session2.

The output from vncserver_submit gives you several steps to follow.

  1. Run a "tunnel" command in your local terminal to establish SSH tunneling. You can do this in the native SSH client on your desktop or laptop, or copy and paste the information into an SSH client such as PuTTY for Windows. Follow this link for an example of how to do it using PuTTY SSH client in Windows.
  2. Start the TurboVNC client on your local machine as described just below.
  3. Copy and paste a "localhost:nnnn" string into your TurboVNC dialog box.

Start the TurboVNC client

Run the TurboVNC client on your local system, following these examples.

Linux and Mac OS X

Open an X terminal application and run vncviewer on your command line with the "localhost:nnnn" output.

vncviewer localhost:nnnn


Select TurboVNC Viewer from the Start Menu TurboVNC group on your desktop.

Paste the "localhost:nnnn" string in the dialog box and click Connect.

New TurboVNC Connection

You may notice that the string is shortened automatically at this point.

Standard VNC Authentication


Next, you will be asked to enter a one-time authentication password. This password is provided to you when you run the tunnel command. If you wish to reconnect to an active VNC session, run that command again to generate a new one-time password or run vncserver_submit again.

If TurboVNC reports an inability to connect, make sure that:

  • you correctly entered your one-time password.
  • the VNC host is the one specified by the vncserver_submit script that you ran; localhost is always the same, but the port may be different.
  • that you did Step 1 (above) correctly to establish the ssh tunnel.
  • that your local firewall is not blocking connections from the local TurboVNC to the local ssh tunnel. Check your firewall instructions or see your system administrator for assistance.

Run your application

Open a terminal within your TurboVNC client window. (Select Applications, then System Tools, then Terminal.)

Load the module for the desired application using the module load command.

module load vapor

Then, start the application by running the executable as usual. The GUI should display in the virtual desktop.


When you are finished with your application

It is important to close all TurboVNC client windows before closing your local terminal or killing the SSH tunnel. Failure to do so can result in frozen client windows that may be difficult to close.

Follow these steps:

  1. Close your TurboVNC client window.
  2. Terminate the tunnel to the VNC host.
  3. Kill your batch job or let it shut down when the wall-clock limit is reached.

Leave the batch job running if you are simply taking a break and plan to return to the session later on.

* Both ParaView and VisIt have their own built-in remote display capabilities. See each application's web site for details.