Lehmus is the University of Oulu’s own High Performance Computing (HPC) environment. If you are a student or staff member at the University of Oulu, you can use Lehmus for research and course work. Lehmus provides interactive sessions in a Linux desktop environment with access to the university’s software library. You can also utilize Lehmus for batch jobs for HPC workloads that you are developing yourself, or that you cannot run on CSC’s national supercomputers (see: CSC: High-performance computing.)

Pocket guide to Lehmus

• Accessing the cluster
  • SSH Access to login nodes
  • Accessing the portal
• Storage and how to handle my datasets
  • Requesting Lehmus project storage
• Cluster configuration and what can I use
• Accessing software
  • Requesting software to Lehmus

Accessing the cluster

Accessing Lehmus is easy. You can utilize one of two ways to connect:

1. Using SSH to login one of login nodes
2. Using your favorite browser to access https://lehmus.oulu.fi portal.

In both ways, you must use your University of Oulu account. In ssh, you should use the short version of your username (so no @univ.yo.oulu.fi or @student.oulu.fi at the end, just the username). In the portal, you must use the full format to login, i. e. username@univ.yo.oulu.fi or username@student.oulu.fi.

SSH Access to login nodes

You can use your University of Oulu account to login. All modern operating systems have built-in ssh client on terminal. Most systems have the terminal named as Terminal or in older Windows it is cmd or PowerShell.

When you have terminal open, type following command with your username and press enter. After that it will ask your password and you can type it. As usual Linux software, it will not print anything to terminal when you type. So don’t worry if it seems like your password isn’t typed in.

PS C:\Users\username> ssh lehmus-login1.oulu.fi -l username

username@lehmus-login1.oulu.fi's password:

Last login: Wed May 21 02:47:37 2025 from 130.231.12.169

[username@lehmus-login1 ~]$

When you see

lehmus-login1 ~]$

you are in the system, and you can move forward.

Login nodes

lehmus-login1.oulu.fi

Accessing the portal

If you don’t know how to utilize the command line, you can utilize the Lehmus from your browser using the Open OnDemand portal. This will allow you to access graphical desktop if your software requires GUI for analyzing results or setting up the simulation. Larger simulations should always be run on non-interactive sessions. Portal is available on https://lehmus.oulu.fi and it can be accessed from EU/ETA region. From other parts of the world, you must use VPN.

Storage and how to handle my datasets

Now, you have accessed the system and you want to start to run simulations. Now the question is, where can I store my data?

First storage option is your home folder but it isn’t suitable for larger datasets. The home folder is meant to store your personal files and it is limited to 5 GB. If you are utilizing Lehmus, you can request to increase it to 50 GB free and after that it will cost 0.15 EUR /GB/Year to your research unit.

Second option is to request /research folder for your research project. This is similar to home folder but more than one person can use your project folder. This is best place to store your results and datasets. This storage will cost same 0.15 EUR /GB/Year and it will include backups like home folder.

Now we can move to Lehmus specific storage. We offer /scratch and /local storage to use as temporary storage. Both are free to use. /scratch is shared between nodes and you can request it for your project. On default we will provide 1 TB of storage. This storage will not have backups.

Last we have node local storage called /local. This is limited space storage and it is available on our newest nodes. You can utilize it on jobs by referring to environment variable $LOCAL_SCRATCH. This storage will be cleared after the job end so it will not work for long term storage.

/homedirXX/username

/research/project_name

/scratch/project_name

/local

Requesting Lehmus project storage

You can request Lehmus project storage by sending following information to ict@oulu.fi:

• Project name:
• Project Description:
• Project start date:
• Project end date:
• Project Owner:
• Project Members:
• Quota for /research directory:
• Quota for /scratch directory:
• Cost Center:
• Permission from supervisor:

After requesting the Lehmus project, you will get confirmation message and extra information how to manage the project.

Cluster configuration and what can I use

Now you have access to cluster and storage to where to store data. Now we can check how to utilize the Lehmus and it’s SLURM configuration.

Lehmus contains following partitions: Basic time limit on lehmus is 14 days for normal jobs and 7 days for interactive jobs. Please don’t overuse this time limit because we may limit to shorter to allow fair access to computing resources to everyone.

Now we know partitions where we can run jobs. Next we should check the features that our nodes have to limit jobs in specific nodes.

And latest, some of our nodes have GPU’s available and we below you can see them:

And for quick reference, nodes in the system on July 4, 2025:

Accessing software

On Lehmus cluster software is available on environment modules system. You can access it with module command. Environment modules system is build to allow you to load specific software to use and configure your terminal to have all required environment variables and sometimes license files on your home directory.

When you try to find out if software is available on Lehmus,

1. check if the software is just available on shell by typing the command to start it.
2. If the software is not available, try to find it on modules system.
3. If it isn’t available here, you can ask ICT to install it.

You can list all available softwares with command module avail

You can load specific software using module load software or specific version using module load software/version.

If you want to remove software from your environment, you can use module unload software or if you want to remove all modules, you can use module purge.

Sometimes loading will reveal more software that are available to use. This feature is used when you example load new compiler to use and then you can see specific libraries that have been build for that compiler. This is also used with cluster libraries like MPI to make sure that you are using right compiler+mpi combinations to run your software.

Requesting software to Lehmus

If you need new software to Lehmus, please send following information to ict@oulu.fi

• Software Name
• Description of software
• Software license type
• If software requires license, do you have it?
• Software installation instructions
• Software package if we can download it, otherwise we will ask you to provide it
• Does software requires user access management
• Other useful information

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