Glossary

A quick reference for all technical terms used in this guide, listed by chapter.

Chapter 1: Welcome

Term	Definition
supercomputer	A very powerful computing system made up of thousands of interconnected computers (nodes) working together.
Command Line	A text-based interface where you type commands to interact with a computer, instead of clicking with a mouse.
HPC	High-Performance Computing. The use of supercomputers and parallel processing to solve large computational problems.
High-Performance Computing	The use of supercomputers and parallel processing to solve large computational problems.
Terminal	The application on your computer that provides access to the Command Line (Terminal on Mac/Linux, PowerShell on Windows).
LLM	Large Language Model. An AI model with billions of parameters trained on massive text datasets to understand and generate language.

Chapter 2: The keys to the castle

Term	Definition
OS	Operating System. The core software that manages a computer's hardware and runs your programs, such as Windows, macOS, or Linux.
SSH	Secure Shell. A protocol for securely connecting to a remote computer over the internet.
phishing	A type of cyberattack where attackers deceive people into revealing sensitive information, such as passwords, by pretending to be a trustworthy entity.
cryptographic	A secure way of protecting information using mathematical algorithms so that only the right people can access it.
SSH Keys	A pair of cryptographic keys (one public, one private) used to authenticate your identity when connecting to LUMI.
SSH Key Pair	A pair of cryptographic keys (one public, one private) used to authenticate your identity when connecting to LUMI.
Private Key	The secret half of your SSH Key Pair. It stays on your computer and should never be shared.
Public Key	The shareable half of your SSH Key Pair. You upload it to the LUMI portal so LUMI can verify your identity.
passphrase	A password that protects your Private Key, adding a second layer of security.
string	A sequence of characters, such as letters, numbers, and symbols, used in computing to represent text.
Key fingerprint	A unique short sequence of characters used to identify a longer public key, allowing you to verify that you are connecting to the genuine server and not an impostor.

Chapter 3: The Command Line

Term	Definition
script	A list of commands saved in a file that LUMI can execute automatically, even while you're away.
Shell	The program that interprets and executes your typed commands.
CLI	Command Line Interface. Another name for the Command Line - a text-based way to interact with a computer.
Command Line Interface	Another name for the Command Line - a text-based way to interact with a computer.
directory	The command-line term for "folder."
Working Directory	The directory you are currently "inside" in the Command Line. Shown by the `pwd` command.
`$HOME`	Your personal user directory on LUMI, located at `/users/<username>`. Where you land after logging in.
Parent Directory	The directory one level "above" the current one. Reached with `cd ..`

Chapter 4: Navigating LUMI

Term	Definition
Node	An individual computer within the LUMI supercomputer.
Login Node	A shared "lobby" node where you manage files and submit Jobs. Not for heavy computation. Named `uan01`, `uan02`, etc.
Compute Node	A powerful node reserved exclusively for running your Jobs. Named like `nid007628`.
Job	Any task you ask the supercomputer to run - a script that trains a model, processes data, or runs a simulation.
processor	The "brain" of the computer that carries out instructions and calculations. Often used interchangeably with CPU.
CPU	Central Processing Unit. The general-purpose processor of a computer. Handles complex tasks sequentially.
GPU	Graphics Processing Unit. A specialised processor that is incredibly fast at doing many simple calculations at the same time. Essential for AI.
hardware	The physical components of a computer system, such as processors, memory, and storage drives.
Partition	A group of nodes with specific hardware and resource limits (e.g., `small-g`, `dev-g`).
Slurm Partition	A subdivision within a hardware Partition that sets limits on Job size, duration, and number of concurrent Jobs (e.g., `standard`, `small-g`, `dev-g`).
TB	Terabyte. A unit of digital data storage equal to 1,024 Gigabytes (GB).
`/project`	Shared project storage (50 GB). Good for files the whole team needs.
`/scratch`	High-capacity temporary storage (50 TB). Your main working area for datasets, outputs, and checkpoints.
`/flash`	Ultra-fast temporary storage (2 TB). 3x more expensive - use only when your Job needs very fast I/O.
LUMI-C	The CPU Partition of LUMI - nodes with powerful processors but no GPUs.
LUMI-G	The GPU Partition of LUMI - nodes equipped with AMD MI250X GPUs for AI workloads.
walltime	The maximum duration a Job is allowed to run before it is stopped.
I/O (Input/Output)	The speed of reading from and writing to a storage drive.
NVMe	Non-Volatile Memory Express. A type of extremely fast flash storage drive.
GCD	Graphics Compute Die. One independent half of an AMD MI250X GPU chip. Each MI250X contains 2 GCDs, each with its own 64 GB of VRAM. Slurm treats each GCD as a separate GPU.
encryption	A method of protecting data by converting it into a secret format. Only people with the correct password or key can unlock and read it.
GDPR	General Data Protection Regulation. A European Union regulation concerning data protection and privacy in the EU and the EEA.
Data Controller	Under GDPR, the entity that determines the purposes and means of processing personal data.
Data Processor	Under GDPR, the entity that processes personal data on behalf of the Data Controller.
Data Processing Agreement (DPA)	A legally binding contract between a Data Controller and a Data Processor regulating the secure handling of personal data.

Chapter 5: AI software on LUMI

Term	Definition
Lustre	LUMI's high-performance filesystem, optimised for large files but sensitive to many small files.
pip	Python's standard package manager - a tool that automatically downloads and installs Python libraries from the internet.
`pip list`	A command to display all Python packages (libraries) currently installed in your environment or Container.
library	A collection of pre-written code that you can plug into your own programs to perform common tasks (e.g., PyTorch for AI calculations).
software	The programs, applications, and scripts that run on the hardware to perform tasks.
Container	A single `.sif` file that packages all your software, libraries, and dependencies into one "box."
Apptainer	The Container tool used on LUMI. A secure, supercomputer-friendly alternative to Docker.
Singularity	The Container tool used on LUMI. A secure, supercomputer-friendly alternative to Docker.
Bindings	Configuration that allows a Container to communicate with LUMI's hardware (GPUs, high-speed network). Set up by loading the `lumi-aif-singularity-bindings` Module.
Runscript	A set of default instructions baked into a Container that define what happens when you `singularity run` it.
`venv`	Virtual Environment. A private, self-contained folder where you install Python libraries for a specific project so they do not interfere with other projects on the system.
Virtual Environment	A private, self-contained folder where you install Python libraries for a specific project so they do not interfere with other projects on the system.
Module	A pre-installed software package on LUMI that you activate with `module load`.
PyTorch	A popular open-source machine learning framework used for deep learning and artificial intelligence.
Docker	A popular platform for building and running software in isolated Containers.

Chapter 6: GitHub

Term	Definition
GitHub	The world's largest platform for hosting and sharing code.
Git	The version-control tool that tracks changes to code. Pre-installed for every user on LUMI.
Repository	Aka repo. A project folder on GitHub that contains code, configuration files, and history of all changes.
`git clone`	Downloads a Repository from GitHub to your LUMI storage.
`git pull`	Updates your local copy of a Repository with the latest changes from GitHub.

Chapter 7: Slurm

Term	Definition
Slurm	The Job scheduler that manages who gets to use which Compute Nodes and when.
Batch Script	A text file containing Slurm options and commands that define what resources you need and what to run.
`sbatch`	The command to submit a Batch Script to Slurm.
`squeue`	The command to check the status of your queued or running Jobs.
`scancel`	The command to cancel a running or pending Job. Use `scancel <job_id>` or `scancel --me` to cancel all your Jobs.
Interactive Job	A Job where you get a live Terminal session on a Compute Node for real-time work (debugging, testing).
Billing Unit (BU)	The unit of currency for LUMI compute time. Different resources (CPU, GPU, storage) cost different amounts of BUs.
`srun`	The command to start an Interactive Job or to launch a task within an allocated Job.
GPU-hours	One of the two currencies of Billing Units on LUMI. Used for compute time on the LUMI-G GPU Partition.
CPU-hours	One of the two currencies of Billing Units on LUMI. Used for compute time on the LUMI-C CPU Partition.
Environment Variable	A background setting you define before running a program, which tells the program how it should behave (such as telling it which AI model to load or where to save files).
vLLM	A fast software engine used to run LLMs efficiently. It is the recommended way to use large language models on LUMI.
log	A text file that automatically records the output, progress, and errors of your programs as they run. Slurm saves these as `.out` files.

Chapter 8: Graduation & next steps

Term	Definition
MCP	Model Context Protocol. An open standard that lets AI assistants connect to external tools and data sources - for example, letting your chatbot search the LUMI documentation.