Resources Access Guide

Overview

This guide explains how to request access, configure SSH authentication, and connect to the SCI-UC Advanced Computing Resources.

1. Request Access

To access the SCI-UC clusters and its computing and storage resources, you must first request an account by following the instructions provided in the official documentation:

Request Access

This guide explains the required information and steps to submit your access request.

2. SSH Key Requirement

Access to SCI-UC managed clusters is strictly provided via frontend nodes (ui.sci.unican.es) through secure SSH connections using public-key authentication.

2.1 Generate a New SSH Key

On your local machine, run:

ssh-keygen -t ed25519 -f ~/.ssh/id_ed25519-ui

When prompted:

  • Enter a secure passphrase
  • Press Enter to accept the default file location

This will generate:

  • Private key: ~/.ssh/id_ed25519-ui
  • Public key: ~/.ssh/id_ed25519-ui.pub

2.2 Send Your Public Key

Display your public key:

cat ~/.ssh/id_ed25519-ui.pub

Copy the full output and send it to:

soporte.sci@unican.es

Include:

  • Your username (if known)
  • A short request to install your SSH key
  • The full contents of your public key

3. Connect to the Clusters

Once your request is approved, you will receive your username.

To connect:

ssh -i ~/.ssh/id_ed25519-ui <username>@**ui.sci.unican.es**

You will be prompted for your SSH key passphrase.

4. Access from Windows - PuTTY (Optional)

4.1 Basic Configuration

Use the following connection details:

  • Hostname: ui.sci.unican.es
  • IP: 193.144.184.31

Steps:

  1. Enter the hostname or IP
  2. (Optional) Save the session
  3. Click "Open"

putty1

4.2 Set Default Username (Optional)

To avoid entering the username each time:

Connection → Data → Auto-login username

Save the session after configuring it.

5. Once Logged In

After connecting to the UI node, you can:

  • Submit jobs using Slurm (srun, sbatch, salloc)
  • Access shared storage ($HOME, Lustre)
  • Transfer files using scp or rsync

6. Resource Limits on the UI Node

The UI node is intended for lightweight tasks only.

Check your limits with:

ulimit -a

6.1 Enforced Limits

Resource Soft Limit Hard Limit Description
Memory (virtual) 2 GB 4 GB Per process
Processes (nproc) 512 1024 Max processes/threads
CPU time 120 min 240 min Per process

For heavy computations, use the Slurm scheduler.

7. Cron Jobs

You can schedule lightweight background jobs on the UI node.

7.1 Edit Cron Jobs

crontab -e

7.2 List Cron Jobs

crontab -l

Note: Cron jobs are subject to the same resource limits as interactive sessions.