CRC - NOTS OnDemand: A Graphical Interface to NOTS

Information and tips for using interactive applications on the NOTS cluster via the Open OnDemand portal.

NOTS OnDemand is a graphical interface to the NOTS cluster, which you can access through your web browser. It provides an easy way to run user-friendly interactive applications that make use of the cluster's computational and storage resources.

NOTS OnDemand is currently in beta-testing, so:

only a subset of NOTS users may run the apps at this time (though for technical reasons, all NOTS users are able to log in to the portal),
features and apps are likely to evolve quickly as we make adjustments to better suit our user community, and
these associated documents are also likely to change frequently.

To provide feedback on NOTS OnDemand or on these documents, please submit a request and be sure to mention "NOTS OnDemand" in the subject line.

NOTS OnDemand is for Interactive Tasks

Interactive means you are actively working with software on NOTS, not just babysitting code that runs on its own for hours.

NOTS OnDemand is intended to allow interactive applications to have minimal waiting time in the job queue, so that users like you can get started with their interactive work quickly.

To keep the waiting time low, we ask that users not run OnDemand jobs for longer than necessary. For example, please do not let an interactive job sit idle for a long period of inactivity, as that wastes computing resources. If you need to step away from your computer for a while, you can always save your work and stop/cancel your NOTS job, then start a new job once you get return to the computer.

Please also do not abuse the interactive applications to run non-interactive tasks. If your code needs to run for a long time, you should convert it into a (non-interactive) script and submit it as one or more jobs on one of the main partitions, such as commons. Please see CRC NOTS Available Accounts, QOS, and Partitions in SLURM for more information on those partitions.

You can use the NOTS Desktop or the NOTS Shell Access app to get to a command prompt and submit a SLURM job with sbatch.

Accessing the NOTS OnDemand Interface

Just like with the SSH interface to NOTS, you must be on the Rice network in order to connect to NOTS OnDemand. Please see CRC Access to Shared Computing Resources for more details.

Once you are on the Rice network, point your web browser to:

https://ondemand.crc.rice.edu/

then proceed to login with your Rice NetID and password.

Available Applications

There are two kinds of applications available via NOTS OnDemand:

Immediate Applications

These applications run on the web server, and start as soon as you click on them.

Icons of the three immediate apps as shown on the NOTS OnDemand home page

Active Jobs -- Shows a list of jobs queued or running on the NOTS cluster, similar to the output of the squeue command. You may choose to see just your jobs, all jobs in the queue, or a subset of jobs that match a search term.
Home Directory (also the Files menu) -- Provides a graphical explorer for your files on NOTS that allows you to view, move, copy, delete, upload, and download files.
NOTS Shell Access -- Connects you to a command-line interface on a NOTS login node, similar to what you would see by SSHing into NOTS. This application would be useful for running bash commands in preparation of, or instead of, launching an interactive application.

Job-Based Interactive Applications

These applications are more powerful and require you to run them via a SLURM job so that the software is executed on one of the NOTS compute nodes. The next session explains that process in more detail.

Icons for the four job-based interactive apps on the NOTS OnDemand home page.

JupyterLab Server -- Work with Jupyter Notebooks. Currently this runs a default Python environment based on a multitude of Python packages already installed on the NOTS cluster via the Module system.
- Soon: We will provide information on accessing your own software environments from JupyterLab.
RStudio Server -- The R Studio interactive development environment (IDE) for the R language.
MATLAB - The MATLAB interactive development environment (IDE).
- The MATLAB bug previously mentioned here has been fixed. Please feel free to try out this app.
NOTS Desktop -- A Linux desktop environment, similar to a remote desktop connection to a workstation, except the "workstation" is a NOTS compute node! The environment includes typical applications such as a file manager, a web browser, text editors, a Terminal for executing command-line commands, etc.
- You can execute just about any interactive software installed on NOTS using this app, without wrapping it in a SLURM script or setting up SSH tunnels. Just open the Terminal, load the required modules, and type the command that runs your software!

(More applications will be added over time.)

Launching Job-Based Applications

When you start one of these applications, you are presented with a web form asking a few questions. The form remembers your previous answers, so if you launch an app multiple times, you probably don't have to fill in every answer each time.

The form first asks two mandatory questions about what computing resources your application requires. Following that are optional questions that can affect how your job is run.

This table presents the questions and the explanations of how to answer them.

Table of submission form questions, how to answer them, and reference images
Question and How to Answer	Reference Image of the Question in the Form
Runtime (in hours) -- Specify how many hours of real-world time (as measured by a "clock on the wall") your job should be allocated. Valid times are between 1-6 hours. This time is measured from when the job starts running. WARNING: Once its runtime runs out, your job will be immediately stopped by the scheduler. Pay attention to how much time your job has left to avoid surprises.
Resource Request Size -- Specify the number of compute cores and the amount of main memory (RAM) your job requires to run. These are kept at a fixed ratio to make it easy to decide which one to pick. Choose the smallest option that allows your job to run to completion. If you choose more resources than your job actually needs, you waste resources and prevent other users from accessing them. If you're not sure what you need, try your job with the "Small" setting. If your job runs out of memory or needs more processing cores to do the work, run it again but choose "Medium". Continue to retry and increase the setting until it runs successfully. Please let us know whether or not the available choices meet your needs.
I would like to receive an email when the session starts (optional) -- Check this box if you want NOTS OnDemand to send you an email once your requested job begins to run. This is mainly useful if your job is likely to spend a long time in the queue before starting to execute. The CRC generally aims to prevent long waiting times for NOTS OnDemand jobs.
Working Directory (optional) -- This is the directory on NOTS where your job begins running. The default is your home directory, but you can change it to something else, such as: `/scratch/<your-netid>` You can either type a path into the text box, or use the [Select Path] button to choose a path from a file explorer interface.
Reservation (optional) -- If you have access to a NOTS reservation (high-priority access to compute nodes), you may enter the reservation name here to run your job using that reservation. The CRC typically allocates reservations for classes; your instructor should let you know if this is the case.
Launch -- When the form is completed, press this button to submit your job to the queue.