Getting Started

Prerequisites

Before connecting, you need:

• A Prometheus account (request one through your MRG leader)
• An OpenSSH-compatible client
• Your registered SSH private key
• Basic familiarity with the Linux command line

Generate SSH Keys

The Prometheus cluster uses RSA key authentication for secure access. You need to generate a public/private key pair. Skip this section if you already have a registered Prometheus key.

Create an SSH key

macOS or Linux

ssh-keygen -t rsa -b 4096 -f ~/.ssh/id_rsa
chmod 600 ~/.ssh/id_rsa

Windows

Open PowerShell and run:

ssh-keygen -t rsa -b 4096 -f "$HOME\.ssh\id_rsa"

This creates:

• id_rsa: your private key; never share it
• id_rsa.pub: the public key to send to your MRG leader or cluster administrator

Request Cluster Access

1. Send your public key to your MRG leader
2. Request a Prometheus account
3. Wait for account confirmation

Add Passphrase (Optional but Recommended)

For additional security, add a passphrase to your key:

ssh-keygen -p -f ~/.ssh/id_rsa

Configure SSH

Prometheus is reached through the CyI HPC bastion. SSH handles the additional hop automatically. The same Prometheus username and private key are used for the bastion and the Prometheus login node. Your private key remains on your computer.

macOS

touch ~/.ssh/config
chmod 600 ~/.ssh/config
open -e ~/.ssh/config

Linux

touch ~/.ssh/config
chmod 600 ~/.ssh/config
nano ~/.ssh/config

Windows

Open PowerShell:

notepad "$HOME\.ssh\config"

Save the file as config, without a .txt extension. Native Windows OpenSSH reads it from C:\Users\<Windows-user>\.ssh\config.

SSH configuration

Add the following configuration in your SSH config file, replacing <your-username> with your Prometheus username and <path-to-your-private-key> with the path to your private key (e.g., ~/.ssh/id_rsa):

Host cyens-bastion
    HostName bastion.hpcf.cyi.ac.cy
    User <your-username>
    IdentityFile <path-to-your-private-key>
    IdentitiesOnly yes

Host prometheus
    HostName prometheus.cyens.org.cy
    User <your-username>
    IdentityFile <path-to-your-private-key>
    IdentitiesOnly yes
    ProxyJump cyens-bastion

Connect to Prometheus

Once your account is activated and your SSH configuration is set up, connect using:

ssh prometheus

The connection path is:

Your computer → CYENS bastion → Prometheus login node

After logging in, verify your session:

hostname
whoami

First Login Setup

Check Your Environment

# Check current directory
pwd

# List available partitions
sinfo

# Check your groups
groups

# View your home directory quota
quota -us

Understand the File System

# Your home directory (20GB limit)
ls -la /trinity/home/$USER

# Shared group storage (30TB per group)
ls -la /lustreFS/data/

# Check group quota
lfs quota -gh <group-name> /lustreFS/

Cluster Architecture Overview

The Prometheus cluster consists of:

Head Node

• Login and job submission point
• DO NOT run compute jobs here
• Used for file management and job scheduling

Compute Nodes

• gpu[01-08]: 8 nodes with A5000 GPUs (8 GPUs each)
• gpu09: 1 node with A6000 Ada GPUs (4 GPUs)
• 512GB RAM and 32 CPU cores per node

Storage Systems

• /trinity/home/: Personal home directories (SSD, 20GB limit)
• /lustreFS/data/: Shared group storage (305TB Lustre filesystem)
• Local storage: 1TB NVMe on each compute node

Important Usage Rules

Checking Cluster Status

# View partition information
sinfo

# Check job queue
squeue

# Check your running jobs
squeue -u $USER

# View detailed node information
scontrol show nodes

Example sinfo output:

PARTITION AVAIL  TIMELIMIT  NODES  STATE NODELIST
defq*        up   infinite      6  idle~ gpu[03-08]
defq*        up   infinite      1    mix gpu02
defq*        up   infinite      1   idle gpu01
a6000        up   infinite      1    mix gpu09

Next Steps

Now that you’re connected to Prometheus:

1. Set up your development environment - See Environment Modules
2. Learn about partitions and queues - Read Partitions & Queues
3. Submit your first job - Follow Job Submission
4. Configure VS Code (optional) - See VS Code Setup

Getting Help

• Cluster status: Use sinfo and squeue commands
• Support: Contact your MRG leader
• System issues: Report to cluster administrators

Common First-Time Issues

“Permission denied (publickey)”

• Verify your public key was added to the cluster
• Check your SSH config file syntax
• Ensure private key permissions are correct (chmod 600)

“Connection refused”

• Verify the hostname: prometheus.cyens.org.cy
• Check if you’re connected to the internet
• Confirm your account is activated

“Quota exceeded”

• Home directory has a 20GB limit
• Use group storage in /lustreFS/data/ for large files
• Check usage with quota -us