Data: Visualization: Running Remote Visualization Jobs on Maverick

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Running Interactive Jobs Through a Web Browser

Maverick's 3D graphics capabilities can be used from other locations for any OpenGL application using VNC and VirtualGL. The preferred and simplest way to do this is via a Java-based web interface. This requires only a Java-enabled web browser and a terminal with which to log into maverick to start the VNC session.

Starting a VNC Session

If you are new to VNC you will need to set up a VNC password on maverick. To do this, run

vncpasswd

This can be done at any time to change your VNC password, but must be done at least once before your first session. Once you have a vnc password:

1. Login to maverick with ssh:

   ssh @maverick.tacc.utexas.edu

2. Submit the session as an interactive job:

   qsub /usr/local/qsub/RUN.vnc

3. Look in the file ~/vnc_url to find the URL for your VNC session
4. Visit this URL to log in to your VNC session

Your browser should ask you for a password. Enter your VNC password (not your maverick login password) and you will be presented with a maverick desktop in your web browser. Though this looks very much like a standard X Windows desktop, it differs in that all rendering is performed on maverick. You can even connect to the session through multiple browsers on different machines simultaneously if you want to have your display mirrored on other displays for presentations or demonstrations.

Alternatively, once you have set your VNC password, you can also launch the VNC server on Maverick through a Web interface on the TeraGrid Visualization Gateway.

Running a Graphics Job Over the VNC Session

Once your VNC session is running and you have access to the maverick desktop, you can very easily run any application. To run a graphics application (my_graphics_app for example), use the following command:

vglrun my_graphics_app

Running Interactive Jobs Through a VNC Client

For optimal performance, Maverick can also be accessed using VNC with a stand-alone VNC client, rather than via a web browser. The recommended client software is TurboVNC, and can be downloaded from the VirtualGL Homepage

The latest release of TurboVNC can be found under "Latest Releases." Under certain conditions, the TurboVNC viewer can deliver as much as 2-3 times the performance of the web viewer. The TurboVNC viewer also supports double buffering, which results in significantly smoother animation. Note that while TurboVNC provides optimal performance, other stand-alone VNC clients may work as well.

To connect to your VNC session using a stand-alone VNC client:

1. Submit the session as described in steps 1 and 2 in Starting a VNC Session.
2. Look in the file ~/vnc_server to find the address of your VNC session.
3. Login to your VNC session by connecting to this address using your stand-alone VNC client. Consult your particular client application's documentation for details on how to do this.

Customizing Your VNC Session

Several parameters of your VNC session can be modified, including the VNC desktop size, job runtime, and number of requested graphics devices. This is done by passing arguments to the qsub command when submitting your job. The syntax and options are summarized below.

Syntax:

qsub [optional arguments] /usr/local/qsub/RUN.vnc

For example, to modify your VNC session to have a desktop size of 1600x1200, a runtime of 2 hours, and use 4 graphics devices, you would use the command:

qsub -v GEOMETRY=1600x1200 -l h_rt=2:00:00 -l gfx=4 /usr/local/qsub/RUN.vnc

Troubleshooting

• If you get an error which includes the message "GLX extension not supported" when you run your application, prefix the command with vglrun as shown in Running a Graphics Job Over a VNC Session
• If you are behind a firewall, you may need to tunnel though it by forwarding the relevant port to some other accessible port. Details forthcoming.

Specific to the Web Interface:

• If your display does not appear to refresh automatically on mouse input, click the "Refresh" button. It should then automatically refresh on input.
• The 'tab' key does not perform auto-complete in your terminal window in the browser. This is because the 'tab' key causes the Java applet to switch focus to the buttons at the top.
• If you have trouble with step 4 in Starting a VNC Session, confirm that Java applet support is available and enabled in your web browser.