RealVNC

1. Overview

Remote desktop allows users to run a real desktop within the cluster environment. This is very useful for users who require to run scientific applications with a GUI seamlessly on the cluster, especially some commercial applications, or visualization applications to render results. It also allows users to disconnect and resume from anywhere without losing the work. On the clusters that HPCS manages we provide the remote desktop service with RealVNC solution.

2. Usage Instructions

To access this service please following these steps:

1. Start the VNC server on the dedicated viz node and record your DISPLAY ID.
   • If you are connecting from within the cluster, for example, if you already have a login session on one of the login nodes, please use the internal hostname, i.e.,
     ssh viz
   • If you are connecting from outside of the cluster, please use the external hostname, i.e.,
     ssh lrc-viz.lbl.gov
   • Start the VNC server on the viz node
     vncserver
   • If above command runs successfully, the last line of the output should look like below,
     New desktop is viz.scs00:1 (10.0.2.15:1)
     The highlighted “1” is your DISPLAY ID and please remember it.
2. Connect to the VNC server with VNC Viewer.
   • The VNC Viewer can be downloaded from here. Chrome browser also has a VNC Viewer extension which can be installed from here and you can launch it directly from the Chrome browser.
   • Connect to the VNC server. In the “VNC Server” field please fill “lrc-viz.lbl.gov:DISPLAY” (without quotes) and replace “DISPLAY” with the actual DISPLAY ID that you obtain from the last step, for example, lrc-viz.lbl.gov:1. You can leave the other options default.
   • After clicking the “Connect” button a window should pop up to prompt you for the username and password. Please fill in your cluster username and the password generated from your OTP device.

After this two steps you should be able to see a VNC Viewer window with a xterm window running, and this is default environment and you can start running your GUI applications.

By default we provide Openbox window manager which is a very barebone yet full-featured and fully configurable window manager. However if you prefer to use your own window manager you can do so as well and below is an example by replacing it with the FVWM which we also provide on the cluster. Please add the following contents to you $HOME/.vnc/xstartup.

targetkbMap=”pc+us+us(intl):2″
xterm -geometry 80×24+10+10 -ls -title “$VNCDESKTOP Desktop” & /global/software/sl-6.x86_64/modules/tools/fvwm2/2.6.5/bin/fvwm-themes-start
vncserver-virtual -kill $DISPLAY

If this file does not exist please create it yourself, and change the permission to 755 with “chmod 755 $HOME/.vnc/xstartup”.

If the desktop is too small for your application, you can change the geometry when starting the VNC server. The proper option is “-geometry WidthxHeight”, e.g., “vncserver -geometry 1024×768“.

If you no longer need the remote desktop any more please shut it down properly to release resource for other users. Simply close the VNC Viewer does not clean the resource on the server. To properly do so, if you are using the Openbox window manager, you need to right click at an empty space within the VNC Viewer window, then click “Log Out” and the vncserver will be shut down. If you are using the FVWM window manager as demonstrated above, you need to click any space area on the desktop to trigger the context menu and then choose “Quit FVWM” then choose “Yes, Really Quit” to shutdown the desktop completely.