Visualisation jobs are interactive jobs that use a GUI or graphical interface to manipulate and otherwise visualise data that may have been produced elsewhere. The visualisation nodes are not directly accessible, so the way to achieve this is to use SSH to forward your VNC session on your personal computer through the login nodes and run the VNC server on the visualisation node using a batch job in the vis queue.
To create a visualisation job you will need to have installed TurboVNC on your desktop or laptop.
The following steps will walk you through the process;
- Start an interactive job on the Visualisation queue, vis, with a default timeout of 1 hour, this can be changed, but is OK for testing. Take note of the node name (vis001 or vis002) for use in step 4. This gives you a terminal session on the selected visualisation node.
- qsub -I -q vis
- Start a TurboVNC server session on the vis node. If this is the first time you have done this your VNC session will need a password setting. This password can be reused, or reset at any time with the vncpasswd command. Once this is done you can start the VNC server.
- take note of the session number (in this case :1) - Desktop 'TurboVNC: vis001.cm.cluster:1 (xyz2)' started on display vis001.cm.cluster:1
- set the DISPLAY env to the session number, in this case export DISPLAY=":1"
- On your client open TurboVNC and in the Preferences select the Security tab
- Under Gateway (SSH server or UltraVNC repeater) enter your userID and the Host: lovelace.lboro.ac.uk. This will automatically set up SSH forwarding when you connect to the node your job connected to. Currently this will be vis002.cm.cluster:5901 (590 for :1, 5902 for :2, etc...).
- You will first be asked for your system password, which establishes the SSH forwarding
- After a short pause, you will then be asked for your VNC session password.
- When connected to the VNC server on the chosen vis node, under the menu item Applications > System Tools, open an Xterm.
- From this point you can run your chosen visualisation software locally
Currently the VNC session doesn't clean up after itself once the job terminates, so it may be an idea to run the following command in the terminal window to see how many sessions you have:
You can kill leftover sessions with the following - just change the session number at the end of the command:
/opt/TurboVNC/bin/vncserver -kill :1