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ARCHER2 hardware

System overview

ARCHER2 is a HPE Cray EX supercomputing system which has a total of 5,860 compute nodes. Each compute node has 128 cores (dual AMD EPYC 7742 64-core 2.25GHz processors) giving a total of 750,080 cores. Compute nodes are connected together by a HPE Slingshot interconnect.

There are additional User Access Nodes (UAN, also called login nodes), which provide access to the system, and data-analysis nodes, which are well-suited for preparation of job inputs and analysis of job outputs.

Compute nodes are only accessible via the Slurm job scheduling system.

There are two storage types: home and work. Home is available on login nodes and data-analysis nodes. Work is available on login, data-analysis nodes and compute nodes (see I/O and file systems).

This is shown in the ARCHER2 architecture diagram: ACRHER2 architecture

Compute node details

The compute nodes each have 128 cores. They are dual socket nodes with two 64 core AMD EPYC 7742 processors.

Note

Note due to Simultaneous Multi-Threading (SMT) each core has 2 threads, therefore a node has 128 cores / 256 threads. Most users will not want to use SMT, see Launching parallel jobs.

Component Details
Processor 2x AMD Zen2 (Romes) EPYC 7742, 64-core, 2.25 Ghz
Cores per node 128
NUMA structure 8 NUMA regions per node (16 cores per NUMA region)
Memory per node 256 GB (standard), 512 GB (high memory)
Memory per core 2 GB (standard), 4 GB (high memory)
L1 cache 32 kB/core
L2 cache 512 kB/core
L3 cache 16 MB/4-cores
Vector support AVX2
Network connection 2x 100 Gb/s injection ports per node

ARCHER2 node diagram

Memory details

The 5,276 standard nodes each have 256 GB and the 584 high memory nodes each have 512 GB. All memory is 8-channel, DDR4 3200MHz with 204.8 GB/s peak bandwidth.

Interconnect details

ARCHER2 has a HPE Slingshot interconnect with 200 Gb/s signalling. It uses a dragonfly topology:

  • Nodes are organized into groups.

    • 128 Nodes in a group.
    • Electrical links between Network Interface Card (NIC) and switch.
    • 16 switches per group.
    • 2x NIC per node.
    • All-to-all connection amongst switches in a group using electrical links.

  • All-to-all connection between groups using optical links.

    • 2 groups per ARCHER2 Cabinet.