Open Ondemand

The OnDemand interface allows you to conduct your research on HTC cluster through a web browser. With OnDemand, users can upload and download files; create, edit, submit and monitor jobs; and run GUI applications (e.g. RStudio Server and Jupyter Notebook), without logging in to the HTC cluster via traditional interfaces.

 

OnDemand was created by the Ohio Supercomputer Center (OSC).  This document provides an outline of how to use OnDemand on the HTC cluster. For more help, check the extensive documentation for OnDemand created by OSC, including many video tutorials, or submit a help ticket.

Start OnDemand

To connect to the HTC cluster via OnDemand, point your browser to https://ondemand.htc.crc.pitt.edu.

  • You will be prompted for a username and password.  Enter your Pitt username and password.
  • The OnDemand Dashboard will open.  From this page, you can use the menus across the top of the page to manage files and submit jobs to the HTC cluster.

To end your OnDemand session, choose Log Out at the top right of the Dashboard window and Close your browser.

Manage files

To create, edit or move files, click on the Files menu from the Dashboard window.  A dropdown menu will appear, listing your directories on CRC file systems. Your home directory is already listed. If you have folders under /mnt/mobydisk/groupshares, and /zfs1 directories, they are also listed. 

Choosing one of the file spaces opens the File Explorer in a new browser tab.  The files in the selected directory are listed.  No matter which directory you are in, your home directory is displayed in a panel on the left.

There are two sets of buttons in the File Explorer.

Buttons on the top of the window on the right perform these functions:

Go To

Navigate to another directory or file system

Open in Terminal

Open a terminal window in a new browser tab

New File

Creates a new empty file

New Dir

Create a new subdirectory

Upload

Copies a file from your local machine to the HTC cluster

Show Dotfiles

Toggles the display of dotfiles

Show Owner/Mode

Toggles the display of owner and permission settings

 If you have files under other directories, which are not listed in the dropdown menu, use the Go To to navigate to the directory.

Buttons on the top left just below the name of the current directory allow you to ViewEdit, Rename, Download, Copy or Paste (after you have moved to a different directory) a file, or you can toggle the file selection with (Un)Select All.

Shell access

You can get shell access to Bridges by choosing Clusters > >_HTC Shell Access from the top menus in the Dashboard window.  In the window that opens, you are logged in to one of HTC login nodes as if you used ssh to connect to the HTC cluster.  

RStudio

You can run RStudio through OnDemand. 

  1. Select Interactive Apps > RStudio Server from the top menu in the Dashboard window.
  2. In the screen that opens, specify the R version, time limit, number of cores. 
  3. Click the blue Launch button to start your RStudio session.  You may have to wait in the queue for resources to be available.
  4.  When your session starts, click the blue Connect to RStudio Server button.  A new window opens with the RStudio interface.  

Errors

If you exceed the time limit you requested when setting up your RStudio session, you will see this error:

Error: Status code 503 returned

To continue using RStudio, go to Interactive Apps > RStudio from the top menu in the Dashboard window and start a new session.

Stopping your RStudio session

To end your RStudio session, either select File > Quit Session or click the red icon in the upper right of your RStudio window.  NOTE that this only closes your RStudio session; it does not close your interactive HTC session. You are still consuming CPU hours on the HTC cluster. 

To end your interactive HTC session, return to the Dashboard window and click the red Delete button.