Tutorial 2: Accessing Anvil

Objective: Log in to the Purdue Anvil supercomputer using the Browser (Open OnDemand) and the Terminal (SSH).

Method 1: Open OnDemand (The Easiest Way)¶

Open OnDemand (OOD) is a web portal that allows you to use the supercomputer entirely through your web browser. No installation required.

1. Navigate: Go to ondemand.anvil.rcac.purdue.edu.

2. Login:

   • Username: Your ACCESS ID.

   • Password: Your ACCESS/XSEDE password.

   • 2FA: Approve the Duo push notification.

Method 2: The Virtual Desktop (For GUI Apps)¶

Sometimes you need to see a graphical interface (e.g., to visualize a molecule using VMD or PyMOL).

1. On the OOD Dashboard, click Interactive Apps > Anvil Desktop.

2. Settings: Set Account to compute and time to 1 hour.

3. Click Launch and wait for the “Launch Anvil Desktop” button to appear.

Method 3: SSH (The “Pro” Way)¶

SSH (Secure Shell) is how professionals access clusters. It is required for tools like VS Code Remote.

🔑 Advanced Setup: Configuring SSH Keys¶

This process creates a digital “handshake” so Anvil recognizes your laptop.

Step A: Generate a Key (On Your Laptop)¶

Open your laptop terminal and run: ssh-keygen -t ed25519

• Press Enter through all prompts.

• This creates a public key file ending in .pub.

Step B: Get your Public Key¶

Print the key to your screen so you can copy it.

Mac/Linux: cat ~/.ssh/id_ed25519.pub Windows: type .ssh\id_ed25519.pub

• Copy the output (it usually starts with ssh-ed25519).

Step C: Install it on Anvil (The “Cheater’s Method”)¶

1. Log in to Open OnDemand.

2. Open Clusters > Anvil Shell Access.

3. Run these commands: mkdir -p ~/.ssh nano ~/.ssh/authorized_keys

4. Paste your copied key into the editor.

5. Press Ctrl+O, Enter to save, then Ctrl+X to exit.

6. Run: chmod 700 ~/.ssh && chmod 600 ~/.ssh/authorized_keys

Step D: Test It¶

Back on your laptop terminal, try to log in: ssh username@anvil.rcac.purdue.edu

Troubleshooting¶

• “Permission denied”: Your SSH key is not correctly installed in authorized_keys. Use Open OnDemand in the meantime.

• “Disk Quota Exceeded”: Your Home directory is full. Move files to your Scratch space.