Zenith Quick Start Guide¶
These new nodes entered Early Access service in August 2026
Important
- This is a service that is in early access and not yet available for projects. Please keep an eye on official channels of communication from the Cambridge RCS team for further information.
- During the Early Access phase, this page will be updated and improved regularly, if you notice something not quite right, please contact support.
Getting Access¶
As mentioned above, this is in early access and so you will be invited to the relevant early access project via our Cambridge Access Portal, Waldur, please follow the guidance found in User Dawn Access as the procedure is the same for Zenith projects.
First Time Accessing Zenith¶
MultiFactor Authentication (MFA) is required, as with all our services. If you are already a user of our services (CSD3, Dawn, Storage, or AIRR) you will already have the appropriate MFA setup.
Otherwise, it is strongly recommended that you read through the MultiFactor Authentication (MFA) user documentation to assist with the setup of your MFA.
Login¶
All Zenith users should initially use the following login nodes to access Zenith resources (Zenith-specific login nodes will be forthcoming):
ssh <username>@login-dawn.hpc.cam.ac.uk
The first time you login, you will be asked to check that the host key fingerprints are correct. Please check that the fingerprints reported match those on the page CSD3 Host Keys before responding yes (NB not y).
You will then be asked for your TOTP Verification code; this is the MFA step mentioned above.
If you cannot connect to the above login nodes, first check that you have received and completed your Zenith project invite, as described above, and have received confirmation that you have been added to the project. If you have checked and received confirmation, please contact support@hpc.cam.ac.uk for further assistance.
Once you have logged in, you will have immediate access to your storage, but for development work you will likely want to request an interactive job using Slurm, as detailed below. This is because the login nodes are currently a different architecture to the Zenith nodes themselves, and also to lessen load on the login nodes.
Hardware¶
Each Zenith (MI355X) node consists of:
- 8x AMD Instinct MI355X GPUs.
- 2x AMD EPYC 9575F processors (64 CPU cores per processor).
- 288 GiB of GPU memory per GPU.
- 64 TB/s aggregate GPU memory bandwidth per node.
Slurm Partition¶
The MI355X (gpu-u-N) nodes are in the mi355x Slurm partition.
Zenith Slurm projects follow the usual CSD3 naming convention for GPU projects and follow the pattern NAME-ZENITH-GPU, containing
units of GPU hours.
Modules¶
To load the Zenith-specific modules run:
module purge
module load rhel9/mi355x/base
This will make available modules tailored to the Zenith architecture. In particular there are modules for the AMD compilers:
module load rocm
The rocm module gives access to the amdclang, amdclang++, and amdflang compilers. These are strongly recommended for CPU codes, and
essential for GPU codes.
The GCC compiler suite is also available via the gcc module.
For MPI codes, there is the openmpi module. This is tied to the rocm compiler suite. If you believe you need MPI with the GCC suite, please
contact support.
For work with python, use either the python module and use python virtual environments or the miniforge3 module and
use conda environments.
Recommendations for running on Zenith¶
To run an interactive job on Zenith, use the sint command, e.g. to request 16 CPU cores on 1 node, with 1 GPU for 10 minutes run:
sint -p mi355x -N1 -n1 -c16 --gres=gpu:1 -A NAME-ZENITH-GPU -t 00:10:00
Note that you will be billed for Zenith GPU hours on interactive jobs.
When compiling codes to run using the Zenith GPUs you should specify the particular AMD architecture by passing
the --offload-arch=gfx950 flag to the AMD compiler you are using. You may also use --offload-arch=native when
compiling on a node.
Problems¶
Please contact support@hpc.cam.ac.uk if you encounter any problems or have any questions