HPC @ Uni.lu

High Performance Computing in Luxembourg

FAQ: How Do I Use Software With Graphical Interface?

If your work requires using a software with graphical interface (GUI) *, you have a choice between:

  • Using X11 forwarding over a regular SSH tunnel;
  • Using the XCS portal (only available within the UL network or through its VPN).

To use X11 forwarding:

  • In Windows:
    • Easiest way: use MobaXterm as SSH client (it can load your existing Putty profiles) to connect to the clusters and start your GUI application as usual in an OAR job;
    • Alternative: install and start VcXsrv, then configure Putty (Connection -> SSH -> X11 -> Enable X11 forwarding) before logging in to the clusters.
  • In OS X: install XQuartz then connect to the clusters with X11 forwarding enabled by ssh -X gaia-cluster or ssh -X chaos-cluster.

  • In Linux: Simply use ssh -X gaia-cluster or ssh -X chaos-cluster to connect and start your application normally under an OAR job.

This is the fastest way to get started and the most flexible (you control all the parameters of your OAR job, etc.) way to have your GUI application running, but it requires a stable and fast network connection.

The XCS portal should be preferred when:

  • you are on a slow network connection (compression makes interaction with the remote desktop more fluid);
  • you are on an unstable network connection (your application will not get killed along with the ssh tunnel);
  • you need to disconnect from viewing your application without interrupting it, and connect to it later.

However in XCS an application profile needs to be created by the HPC sysadmins before you are able to use it, and several profiles already exist.

To use the XCS portal:

  • Log in to https://xcs.uni.lux using your HPC username and password (not! your SSH key’s passphrase, but the password you use to connect, e.g. to GitLab or HPC-Tracker);
  • Install a Java plugin for your browser or install TurboVnc;
  • Select the application profile from the shortcuts list or within the New Visualisation Session menu;
  • Provide the input parameters required to create an OAR job and start your application in the Job submission form;
  • Submit the job and, when it’s status is ‘Active’ in the list of Visualisation Sessions, click on it then:
    • select “Open in new window” to use the Java plugin, or
    • select “View in TurboVNC viewer” to use TurboVNC (if it doesn’t happen automatically, choose TurboVNC to open the extremefactory_session.vnc file your browser is downloading).
[*] Common GUI applications in use on the UL HPC platform: Matlab, RStudio, ParaView, VisIt, Abaqus, SAS, Stata, Allinea DDT/MAP, Nvidia Visual Profiler and others.