Request access to the cluster

To access the cluster and use its computing and storage resources, you must first request an account by sending an email to:

soporte.sci@unican.es

Please include the following information in your request:

  • Full name:
  • Email address:
  • Department / Research group:
  • SSH public key: (see below)

SSH Key Requirement

Access to the cluster is only allowed via SSH key-based authentication. Password logins are disabled.

If you already have an SSH key pair, simply attach your public key file to your request email.

If you need to generate a new SSH key pair, run the following command on your local computer:

ssh-keygen -t ed25519

You can press Enter to accept the default file location (~/.ssh/id_ed25519). Once generated, attach the public key file (id_ed25519.pub) to your access request.

Once you have access to the cluster, you can allow any aditional SSH public key to authenticate on the User Interface node by following these instructions.

Access and Use of the Cluster

Once your request is approved, you’ll receive your assigned username and access confirmation.

You can log in to the cluster’s user interface node (front-end) using SSH:

[user@localmachine]$ ssh user@ui.sci.unican.es

Access from Windows

If you are using Windows, you can connect using an SSH client such as PuTTY. In this documentation page you can find the instructions for accesing the cluster using PuTTY.

Once you have succesfully logged in

Once connected to the front-end node, you can:

Cluster File Systems

The cluster provides several file systems optimized for different purposes. Each user has access to a home directory, a personal working area, and a shared data lake.

PATH File System Size Quota Purpose
$HOME NFS 120G Permanent home directory (configuration files, scripts, source code)
/lustre/$GROUP/WORK/$USER LUSTRE 246T 10T bytes / 1M files Personal working storage
/lustre/$GROUP/DATA LUSTRE 313T 10T bytes / 1M files Common and supervised data lake

User HOME Directories

The home directory is located on an NFS file system and is accessible from all nodes of the cluster.

/nfs/home/$GROUP/$USER

It is designed for:

  • Storing configuration files (.bashrc, .ssh/, etc.)
  • Small scripts and source code
  • Job submission files

Avoid storing large data files or running I/O-intensive operations from your home directory. Use your Personal Working Storage directory instead.

Personal Working Storage

Each user has a WORK directory on the Lustre file system:

/lustre/$GROUP/WORK/$USER

This space is:

  • Accessible from all cluster nodes
  • Intended for temporary and working data
  • Optimized for high-performance parallel I/O

Each user has a storage quota and a file count limit. You can check your current usage with:

[user@ui ~]$ lfs quota -hu $USER /lustre/$GROUP/WORK
Disk quotas for usr usuario (uid 15999):
     Filesystem    used   quota   limit   grace   files   quota   limit   grace
/lustre/geocean/WORK
                 1.197T     10T     15T       -   27149  1024000 1228800       -
  • used: Current usage
  • quota: Soft limit (you will be warned when exceeded)
  • limit: Hard limit (cannot be exceeded)
  • files: Number of inodes used

Shared Data Lake

Each research group also has a shared directory:

/lustre/$GROUP/DATA

This area is intended for:

  • Long-term datasets shared among group members
  • Common input/output data used in multiple projects
  • Data supervised by the group’s PI or data manager

Access is group-wide, and usage is typically monitored by the administrators.

The DATA space is not intended for scratch computations or temporary job files — use your Personal Working Storage area for that.

UI Node Resource Usage Limits

To ensure fair usage and system stability, the following resource limits apply to all users on the login (UI) node.

You can inspect your current limits using the ulimit command:

ulimit -a

Enforced Limits

Resource Soft Limit Hard Limit Description
Memory (virtual) 2 GB 4 GB Total virtual memory per process
Processes (nproc) 512 1024 Maximum number of processes or threads
CPU time 120 minutes 240 minutes Max CPU time per process (accumulated)
  • Soft limits can be increased by the user, up to the hard limit.
  • Hard limits are the maximum values enforced by the system.

For heavy computations or long-running tasks, use the Slurm batch system instead of the login node.

Cron Jobs on the UI Node

Users are allowed to schedule background jobs using the crond service on the login node.

Editing your personal cron jobs:

crontab -e

Viewing your scheduled jobs:

crontab -l

Note: Cron jobs are subject to the same resource limits as interactive sessions. Avoid running heavy jobs via cron on the UI node.

Tips

  • Use srun, sbatch, or salloc for compute jobs.
  • Use cron only for lightweight automation (e.g., syncing files, sending notifications, or monitoring job status).