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GPU Cluster Alpha Centauri

The multi-GPU cluster Alpha Centauri has been installed for AI-related computations (ScaDS.AI).

The hardware specification is documented on the page HPC Resources.

Becoming a Stand-Alone Cluster

The former HPC system Taurus is partly switched-off and partly split up into separate clusters until the end of 2023. One such upcoming separate cluster is what you have known as partition alpha so far. With the end of the maintenance at November 30 2023, Alpha Centauri is now a stand-alone cluster with

  • homogeneous hardware resources incl. two login nodes login[1-2],
  • and own Slurm batch system.


Your new /home directory (from Barnard) is also your /home on Alpha Centauri. Since 5th July 2024, Alpha Centauri is fully integrated in the InfiniBand infrastructure of Barnard. With that, all filesystems (/home, /software, /data/horse, /data/walrus) are available.



The NVIDIA A100 GPUs may only be used with CUDA 11 or later. Earlier versions do not recognize the new hardware properly. Make sure the software you are using is built with CUDA11.

There is a total of 48 physical cores in each node. SMT is also active, so in total, 96 logical cores are available per node.


Multithreading is disabled per default in a job. See the Slurm page on how to enable it.


The easiest way is using the module system. All software available from the module system has been specifically build for the cluster Alpha i.e., with optimization for Zen2 microarchitecture and CUDA-support enabled.

To check the available modules for Alpha, use the command

marie@login.alpha$ module spider <module_name>
Example: Searching and loading PyTorch

For example, to check which PyTorch versions are available you can invoke

marie@login.alpha$ module spider PyTorch
      Tensors and Dynamic neural networks in Python with strong GPU acceleration. PyTorch is a deep learning framework
      that puts Python first.


Not all modules can be loaded directly. Most modules are build with a certain compiler or toolchain that need to be loaded beforehand. Luckely, the module system can tell us, what we need to do for a specific module or software version

marie@login.alpha$ module spider PyTorch/1.12.1-CUDA-11.7.0

  PyTorch: PyTorch/1.12.1-CUDA-11.7.0
      Tensors and Dynamic neural networks in Python with strong GPU acceleration. PyTorch is a deep learning framework
      that puts Python first.

    You will need to load all module(s) on any one of the lines below before the "PyTorch/1.12.1" module is available to load.

      release/23.04  GCC/11.3.0  OpenMPI/4.1.4

Finaly, the commandline to load the PyTorch/1.12.1-CUDA-11.7.0 module is

marie@login.alpha$ module load release/23.04  GCC/11.3.0  OpenMPI/4.1.4 PyTorch/1.12.1-CUDA-11.7.0
Module GCC/11.3.0, OpenMPI/4.1.4, PyTorch/1.12.1-CUDA-11.7.0 and 64 dependencies loaded.
marie@login.alpha$ python -c "import torch; print(torch.__version__); print(torch.cuda.is_available())"

Python Virtual Environments

Virtual environments allow you to install additional Python packages and create an isolated runtime environment. We recommend using virtualenv for this purpose.


We recommend to use workspaces for your virtual environments.

Example: Creating a virtual environment and installing torchvision package
marie@login.alpha$ srun --nodes=1 --cpus-per-task=1 --gres=gpu:1 --time=01:00:00 --pty bash -l
marie@alpha$ ws_allocate -n python_virtual_environment -d 1
Info: creating workspace.
remaining extensions  : 2
remaining time in days: 1
marie@alpha$ module load release/23.04 GCCcore/11.3.0 GCC/11.3.0 OpenMPI/4.1.4 Python/3.10.4
Module GCC/11.3.0, OpenMPI/4.1.4, Python/3.10.4 and 21 dependencies loaded.
marie@alpha$ module load PyTorch/1.12.1-CUDA-11.7.0
Module PyTorch/1.12.1-CUDA-11.7.0 and 42 dependencies loaded.
marie@alpha$ which python
marie@alpha$ pip list
marie@alpha$ virtualenv --system-site-packages /beegfs/ws/1/marie-python_virtual_environment/my-torch-env
created virtual environment in 42960ms
  creator CPython3Posix(dest=/beegfs/.global1/ws/marie-python_virtual_environment/my-torch-env, clear=False, global=True)
  seeder FromAppData(download=False, pip=bundle, setuptools=bundle, wheel=bundle, via=copy, app_data_dir=~/.local/share/virtualenv)
    added seed packages: pip==21.1.3, setuptools==57.2.0, wheel==0.36.2
  activators BashActivator,CShellActivator,FishActivator,PowerShellActivator,PythonActivator,XonshActivator
marie@alpha$ source /beegfs/ws/1/marie-python_virtual_environment/my-torch-env/bin/activate
(my-torch-env) marie@alpha$ pip install torchvision==0.13.1
Installing collected packages: torchvision
Successfully installed torchvision-0.13.1
(my-torch-env) marie@alpha$ python -c "import torchvision; print(torchvision.__version__)"
(my-torch-env) marie@alpha$ deactivate


JupyterHub can be used to run Jupyter notebooks on Alpha Centauri cluster. You can either use the standard profiles for Alpha or use the advanced form and define the resources for your JupyterHub job. The "Alpha GPU (NVIDIA Ampere A100)" preset is a good starting configuration.


Singularity containers enable users to have full control of their software environment. For more information, see the Singularity container details.

Nvidia NGC containers can be used as an effective solution for machine learning related tasks. (Downloading containers requires registration). Nvidia-prepared containers with software solutions for specific scientific problems can simplify the deployment of deep learning workloads on HPC. NGC containers have shown consistent performance compared to directly run code.