Synopsis

Besides accessing Snellius via a terminal, the system can also be used via a web browser using the OpenOnDemand demand service. The service allows users to:

  • manage files
  • work in a shell without using a terminal client on their remote system
  • launch jobs based on predefined templates
  • run interactive web services such as RStudio and Jupyter Notebooks
  • run applications with graphical user interfaces  



Access the OpenOnDemand service.

The Snellius OpenOnDemand service can be accessed via the following URL:

https://ondemand.snellius.surf.nl/

To log in, a valid Snellius login is required, and the Usage Agreement needs to be accepted, see Snellius FAQ.  

Overview

The key features are available in the top menu on the start page:

  • File explorer to upload files to / download from the home directory. Files can be deleted, renamed, moved to a different director or edited online using the integrated online editor
  • Job manager to compose and submit Slurm jobs to the cluster
  • Shell access 
  • Interactive applications 
  • Overview of recent interactive sessions

The file explorer

The file manager can be selected in the top menu. By default, the content of the home directory is shown and can be accessed via a web browser. Other file systems (e.g. a project space or the scratch space) can be chosen under “Change directory”.

Files can be edited using the built-in editor available on the context menu of a file:

Shell access

OpenOnDemand allows users to launch an terminal session on the system without using an SSH client. 
 

To copy and paste into the OPEN OnDemand terminal, use the keyboard shortcuts CTRL+C / CTRL+V

Interactive Sessions

Interactive sessions allows users to execute interactive applications on Snellius. We distinguish two application types:

  1. Server-based application such as Jupyter Notebooks and RStudio. 
  2. Applications with a graphical user interface (GUI) such as MATLAB and Paraview
  3. Application that are indirectly available via the Remote Desktop app such as Ansys, Blender, Firefox and many more. Essentially all installed applications with GUI can be launched in the Remote Desktop app.

Applications can be selected in the Interactive Apps menu. All Snellius users can select on of the preconfigured application. Only UvA FNWI users may also choose their dedicated service, indicated by the prefix “UVA FNWI”. 

After selecting the application, you need to specify the required resources (time and CPUs / GPUs). In most cases 16 CPUs (the smallest possible allocation on Snellius) is sufficient.


After clicking the Launch button, a job is submitted to the specified partition. 

When the requested resource is available, the application can be access via the launch button.

Notice that an interactive session costs budget (one SBU per CPU core and hour). Therefore, it is recommended to terminate the session when the work is done using the Delete button.

Webserver application

When the resources for a webserver-based application are available, you can use the connect button to open the client in a browser, in the example on the left a Jupyter interface. To launch the notebook server, you need to select the Notebook and the Kernel in the New menu.

Virtual Desktop application

In a virtual desktop any  application installed on the system and in the home directory can be executed.

In most cases, you need to open a terminal, load the software module and launch the application from the terminal.

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