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CLASSE-IT 2021 Summer Student Guide

Welcome to the CLASSE 2021 REU, SERCCS, SUnRiSE, and PREM programs. This how-to guide will get you started with IT resources at CLASSE.

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CLASSE User Account

Your CLASSE account username is based on your Cornell NetID, but you must give it a different password. A CLASSE account is required for all the services mentioned in this guide. If you have forgotten or need to reset your password please go to our Password Self Service page.

CLASSE Remote Access Services

X2Go

X2Go is the preferred graphical remote access tool to connect to our Linux systems. X2Go supports the remote execution of X applications, including full Linux desktops.
You will need X2Go to run most Linux applications offered at CLASSE.

Windows 10 Installation

  1. Download the installer from https://wiki.x2go.org/doku.php/download:start
  2. Run the installer (You will need to allow installation at the UAC prompt)

Configuration - creating a new desktop session:
  1. Run the X2Go client on your desktop.
  2. Create a new session with “session | new session…”.
  3. Assign a session name (e.g. CLASSE Grid)
  4. For "Host Name" enter lnx201.classe.cornell.edu
  5. For "Login" enter your CLASSE ID
  6. Choose your desired Session Type:
    • (Recommended) To launch an application on the CLASSE Compute Farm, select Single application, and in the Command field enter:
      python /nfs/opt/CLASSE_GRID/CLASSE_GRID.py
    • For a full desktop session, select Xfce from the "Session Type" drop down list.
  7. Press 'OK' to save the session.

macOS Installation

  1. Download and install the latest version of XQuartzfrom http://xquartz.macosforge.org/landing/
  2. Download and install the latest version of the Mac X2Go client from http://www.x2go.org.

Configuration - creating a new desktop session [screenshots]:
  1. Run the X2Go client in your Applications Folder.
  2. Create a new session with “session | new session…”.
  3. Assign a session name (e.g. CLASSE Grid)
  4. For "Host Name" enter lnx201.classe.cornell.edu
  5. For "Login" enter your CLASSE ID
  6. Choose your desired "Session Type":
    • (Recommended) To launch an application on the CLASSE Compute Farm, select Single application, and in the Command field enter:
      python /nfs/opt/CLASSE_GRID/CLASSE_GRID.py
    • For a full desktop session, select Xfce from the "Session Type" drop down list.
  7. Press 'OK' to save the session.

Configuration - set "X11 application" [screenshots]:
  1. Click on the wrench icon in the X2Go window toolbar.
  2. Under the "General" tab make sure that "X11 application:" is set to /Applications/Utilities/XQuartz.app
    • You will need to restart X2Go if XQuartz was installed while X2Go was running
  3. Click Ok

Linux Installation

  1. Download the installer for your distribution at https://wiki.x2go.org/doku.php/download:start
    • Instructions for each distribution can be found under the section "X2Go Package Repositories for GNU/Linux"

Configuration - creating a new desktop session:
  1. Run the X2Go client on your desktop.
  2. Create a new session with “session | new session…”.
  3. Assign a session name (e.g. CLASSE Grid)
  4. For "Host Name" enter lnx201.classe.cornell.edu
  5. For "Login" enter your CLASSE ID
  6. Choose your desired "Session Type":
    • (Recommended) To launch an application on the CLASSE Compute Farm, select Single application, and in the Command field enter:
      python /nfs/opt/CLASSE_GRID/CLASSE_GRID.py
    • For a full desktop session, select Xfce from the "Session Type" drop down list.
  7. Press 'OK' to save the session.

NoMachine

NoMachine is an alternative graphical remote access tool. NoMachine can be used to access lnx201.classe.cornell.edu, our general-use remote login node. Any CPU- or memory-intensive operations should be run on the CLASSE Compute Farm or on individual workstations, not on lnx201.

Client Installation

  1. Download and install the free "NoMachine Enterprise Client" from: https://www.nomachine.com/product&p=NoMachine%20Enterprise%20Client

Configuration
  1. Start NoMachine
  2. click on "Add"
  3. Fill in the details for your desired connection.
    1. For using lnx201 - our general-use login node (not appropriate for CPU or memory-intensive applications)
      • Host = "lnx201.classe.cornell.edu"
      • Protocol = "SSH"
    2. For using our cloud server to connect to computers on private subnets.
      • Host = "nomachine.classe.cornell.edu"
      • Protocol = "NX"
  4. If Prompted, select "Password" authentication method, and click on "Continue"
  5. If you get a proxy checkbox, leave "Don't use a proxy" selected, and click "Continue."
  6. Change the connection name if desired, and click on "Done."

Connecting

  1. Start NoMachine, and double-click on the connection created above.
  2. The first time connecting, click "Yes" to accept the remote host certificate and verify its identity.
  3. Login with your CLASSE username and password.
  4. Double click on the computer you'd like to control.
  5. Click "OK" to accept the default Audio streaming setting (if desired).

Linux Applications at CLASSE

Ansys

  1. Connect to your CLASSE Grid Session in X2Go
  2. Select Terminal-xfce4 from the list of application in the dropdown menu
  3. Click on Run - This will open a new terminal window
  4. Type the command to open Ansys_2019R2:
    /nfs/opt/ansys_2019-R2/bin/workbench

COMSOL

  1. Connect to your CLASSE Grid Session in X2Go
  2. Select Terminal-xfce4 from the list of application in the dropdown menu
  3. Click on Run - This will open a new terminal window
  4. Type the command to open COMSOL:
    /nfs/opt/COMSOL/52/bin/comsol

GPT

  1. Connect to your CLASSE Grid Session in X2Go
  2. Select Terminal-xfce4 from the list of application in the dropdown menu
  3. Click on Run - This will open a new terminal window
  4. Type the command to open GPT (Please ask your mentor)

Linux Command Line (ls, cd, mv, find, grep etc)

  1. Connect to your CLASSE Grid Session in X2Go
  2. Select Terminal-xfce4 from the list of application in the dropdown menu
  3. Click on Run - This will open a new terminal window
  4. Type the command needed (see table below)
Command Task Example Syntax
ls To list the files in a directory. ls [/tmp]
cd To move into a directory. cd [/tmp]
pwd To show cuurent working directory. pwd
cp To copy a file to another filename or into another directory. cp [file.txt] [/tmp/file.txt]
mv To rename or move a file into another directory. mv [file.txt] [file1.txt]
rm To delete a file. rm [file.txt]
mkdir To create a directory. mkdir [mydir]
find To find a file. find [/tmp] -name [file]
grep To search for text string inside a file. grep [text] [/tmp/file.txt]
less To view the text of a text file, one screen at a time less [/tmp/file.txt]
man To see detailed information about command useage. man [ls]
exit To exit and logout of a Terminal (Terminal-xfce4) session. exit

Other useful shortcuts:
Keystroke Action
up-arrow Show the previous command in your history
tab Complete a command or filename

Mathematica

  1. Connect to your CLASSE Grid Session in X2Go
  2. Select Mathmatica from the list of applications in the dropdown menu
  3. Click on Run

Matlab

  1. Connect to your CLASSE Grid Session in X2Go
  2. Select Matlab from the list of applications in the dropdown menu
  3. Click on Run

Thunar - The Linux File Explorer

Like the "Windows File Explorer", Thunar is a modern file manager.
  1. Connect to your CLASSE Grid Session in X2Go
  2. Select Thunar from the list of applications in the dropdown menu
  3. Click on Run

Text Editors

For a list of available text editors, please see TextEditors. To use any of these editors, simply select it in the CLASSE Grid Session menu. Any editor can also be launched from the Linux command line interface.
How To Launch Emacs:
  1. Connect to your CLASSE Grid Session in X2Go
  2. Select Emacs from the list of applications in the dropdown menu
  3. Click on Run
How To Launch Visual Studio Code:
  1. Connect to your CLASSE Grid Session in X2Go
  2. Select Terminal-xfce4 from the list of application in the dropdown menu
  3. Type the command:
    code

File Storage at CLASSE

Project Files

Most files should stored in the dedicated project space allocated to each research group. Please consult with your mentor on where to store your data and the exact path to any project files that you might need.

User Files

In addition to dedicated project space, user files can be stored in your directory on our UserDisk. Please note that your user directory has a 5 GB quota, so most of your work should be stored in dedicated project areas as described above. Finally, your HomeDisk has a 1 GB quota and should be reserved for essential Linux files like login scripts, browser preferences, source code, etc. Please read HomeDisk, UserDisk, and DataStewardship for more information.

Operating System Share point Path (userid = your username)
Linux UserDisk /nfs/user/userid
  HomeDisk /home/userid
Windows 10 UserDisk \\samba.classe.cornell.edu\user\userid
  HomeDisk \\samba.classe.cornell.edu\home\userid
macOS UserDisk smb://samba.classe.cornell.edu/user/userid
  HomeDisk smb://samba.classe.cornell.edu/home/userid

Accessing Files from Offsite

Connectivity and performance to the file locations above is very dependent on the quality of your internet connection. Because of these performance issues, we highly recommend using Globus when accessing files from outside the lab.

Globus

Globus is a high-speed file transfer system that was originally developed for Grid computing applications. You can use it to copy data remotely from CLASSE central storage to your local computer by following the instructions below:
  1. Browse to https://www.globus.org
  2. Click on "Log In" in the upper-right corner.
  3. Use the scroll-down menu to find Cornell University and then login with your Cornell NetID.
  4. Install Globus Connect personal (For detailed instructions with screenshots see here: https://www.globus.org/globus-connect-personal.)
  5. Connect to a CLASSE endpoint
    1. Click on "Manage Data", and select "Transfer Files".
    2. Click on "Start here ..." and type classe into the search box. You should see the endpoint for "CLASSE" with a path of "/~/".
    3. Select a CLASSE endpoint (add infor for "project path") and log in with your CLASSE credentials.
  6. Connect to your personal endpoint
    1. Click on "Manage Data", and select "Transfer Files".
    2. Click on the second "Endpoint" box, and then the "My Endpoints" tab.
    3. Select the personal endpoint you set up in Step II above.
      • Note that Globus Connect Personal must be running on your computer.
  7. Transfer Files
    1. Navigate through the folders/directories on both endpoints, and use the arrow buttons to transfer data back and forth as desired.
    2. To monitor the progress of a data transfer, click on "Activity".
    3. You will receive an email after each transfer has completed.

Computing Policies and Guidelines

Think before you click!

We see fraudulent emails every day, and they can be quite sophisticated, even appearing to come from someone you know. Make sure you are on a Cornell website before typing in your Cornell password. When in doubt:

Getting Help

If you have any computing questions: For help with central Cornell services, contact IT@Cornell.

Notes for CLASSE Mentors

Connecting to your student's desktop

X2Go Desktop Sharing

X2Go Desktop Sharing can be used by you and your student to connect to the same Linux desktop. See X2Go for instructions.
Zoom Desktop Sharing

Zoom can be used on any platform to view or control your student's desktop (or have them connect to yours).
https://support.zoom.us/hc/en-us/articles/201362673-Requesting-or-giving-remote-control
ScreenConnect

If Zoom or X2Go don't work for what you need, please submit a ServiceRequest and the IT group can help you get setup to use ScreenConnect.

Topic revision: r40 - 06 Jun 2021, WernerSun
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