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ARCHER2 Upgrade: 2023


The information on this page represents our current best understanding of the upgrade but is subject to change and revision as more information becomes available.

Last updated: 2023-03-29

During the first half of 2023 ARCHER will go through a major software upgrade.

On this page we describe the background to the changes, the current information on the timeline, what impact the changes will have for users, any action you should expect to have to take following the upgrade and information on the versions on updated software.

If you have any questions or concerns regarding the upgrade, please contact the ARCHER2 Service Desk.

Why is the upgrade happening?

There are a number of reasons why ARCHER2 needs to go through this major software upgrade. All of these reasons are related to the fact that the current system software setup is out of date; due to this, maintenance of the service is very difficult and updating software within the current framework is not possible. Some specific issues are:

  • Ongoing access to security updates -- the vendor (HPE) can not provide support for security updates for the current system software on ARCHER2 indefinitely, this will be an issue if we continue with the current release.
  • Improvements to interconnect reliability and performance -- the Slingshot interconnect that links compute nodes together and to the high-performance Lustre file systems is currently running an old version of management software that has a number of known limitations and bugs. These affect our ability to monitor the health of the interconnect and have led to reliability issues for calculations using large numbers of compute nodes. Without a major system software upgrade, we cannot move to an up to date version of the Slingshot software that addresses current limitations.
  • Improvements to upgradeability, maintainability and monitoring -- the current system software is based on a collection of early versions from the hardware vendor that do not provide the system health monitoring characteristics of more recent versions or the ability to flexibly update the system with low impact on user service that are available in more recent versions.
  • Access to more recent compilers, software libraries and tools -- the current system software does not provide the ability to access improvements in compilers and libraries (both bug fixes and performance improvements) that are available from HPE. Once the system software is updated, the service will be able to access this improved software.

When will the upgrade happen and how long will it take?

This major software upgrade will involve a complete re-install of system software followed by a reinstatement of local configurations (e.g. Slurm, authentication services, SAFE integration). Unfortunately, this major work will require a long period of downtime but this has been planned with all service partners to minimise the outage and give as much notice to users as possible so that they can plan accordingly.

The current outage dates are:

  • Start: TBC May 2023
  • End: 3-4 weeks after start date

What are the impacts on users from the upgrade?

During the upgrade process:

  • No login access
  • No access to any data on the system

After the upgrade process:

  • Recompile and test code -- as the new system will be based on a new OS version and new versions of compilers and libraries we strongly recommend that all users recompile and test all software on the service. The ARCHER2 CSE service will be recompiling all centrally installed software.
  • Note: there will be no Python 2 installation available as part of supported software following the upgrade. Python 3 will continue to be fully-supported.

Impact on data on the service

  • No data in /home, /work, NVMe or RDFaaS will be removed or moved as part of the upgrade

What software versions will be available after the upgrade?

System software:

  • Base operating system
    • Compute nodes: Cray OS (COS) 2.4.109 based on SLES 15 SP4
    • Login nodes: UAN 2.5.8 based on SLES 15 SP4
  • Slingshot interconnect system software: 2.0.2
  • HPE Cray Management Software (CMS): 1.3.1

Programming environment: 22.12


  • CCE: 15.0.0
  • GCC: 11.2.0 (10.3.0 also available)
  • AOCC: 3.2

Communication libraries:

  • Cray MPICH: 8.1.23
    • Based on MPICH 3.4a2
    • Supports OpenFabrics (OFI) and UCX
  • Cray OpenSHMEMX: 11.5.7

Numerical libraries:

  • Cray LibSci:
  • FFTW:

IO Libraries:

  • HDF5:
  • NetCDF:
  • Parallel NetCDF:


  • Python:
    • numpy: 1.21.5
    • scipy: 1.6.2
    • mpi4py: 3.1.3
    • dask: 2022.2.1
  • R:
  • CrayPAT/Perftools: 22.12.0
  • gdb4hpc: 4.14.6
  • valgrind4hpc: 2.12.10
  • sanitizers4hpc: 1.0.4
  • Lmod: 3.1.4

Summary of user and application impact

For full information, see CPE 22.12 Release Notes

CCE 15

C++ applications built using CCE 13 or earlier should be recompiled due to the significant changes that were necessary to implement C++17. This is expected to be a one-time requirement.

Some non-standard Cray Fortran extensions supporting shorthand notation for logical operations will be removed in a future release. CCE 15 will issue warning messages when these are encountered, providing time to adapt the application to use standard Fortran.

HPE Cray MPICH 8.1.23

Cray MPICH 8.1.23 can support only ~2040 simultaneous MPI communicators.