Isambard User Documentation

Isambard is a HPC service provided by GW4 and the UK Met Office. The system is funded by EPSRC and is one of a number of Tier-2 HPC facilities in the UK.

Isambard is a Cray XC50 system which comprises 20,992 cores, and is one of the world’s first production Arm-based supercomputers. While Isambard is not based on the more common x86 processors from Intel and AMD, most software compiles and runs on Isambard with no or minimal changes.

Each of the 329 compute nodes contain two 32-core Marvell ThunderX2 processors running at 2.5 GHz. 160 nodes have 256 GB and 169 have 512 GB of memory, both at DDR4-2666MHz. The nodes are connected via Cray Aries interconnect in a Dragonfly topology. A Cray Sonexion 3000 storage cabinet provides 900 terabytes of Lustre storage.

Service Status


The Isambard 2 service will shutdown in June 2024 and be replaced with an entirely new Isambard 3 service. Data management is the responsibility of the user therefore we require all important data moved off Isambard 2 before it is shutdown. Support will only be provided for operational issues until the shutdown. Further information will be provided over the coming months.


Since 29 Apr. 2024

XCI system is back in operations following earlier outage.

System Status


28 Feb. 2024

  • Login bastion: Available.

  • XCI (ARM ThunderX2): Available.

  • MACS: Available.

  • A64fx: Available.

  • Phase 3: Available.

Mailing list

An anouncement mailing list is availale to be kept informed of important news regarding the service. Archives and managing your subscription is available at JiscMail GW4-ISAMBARD-COMMUNITY

Acknowledging Isambard

Research outputs that have made use of Isambard should acknowledge the facility by using the following phrase:

This work used the Isambard 2 UK National Tier-2 HPC Service ( operated by GW4 and the UK Met Office, and funded by EPSRC (EP/T022078/1)

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