Japan · operational · hpc

AOBA-S

Operated by Cyberscience Center, Tohoku University at Tohoku University Cyberscience Center .

Phase 1 seed dataset, compiled by hand. These rows were built from public operator, laboratory and vendor sources. A mechanical second-reader pass has since fetched every cited source: 1092 of 1153 systems have a readable citation that names them, and 40 are genuinely weakly sourced. Every claim carries its source and a confidence tier. Treat anything below verified as a lead, not a citation.

Measured performance

Rmax: 17.22 PFlop/s
Rpeak: 19.82 PFlop/s
Rmax ÷ Rpeak: 86.9%
Cores: 64,512
Power: 1.39 MW
Per watt: 12.4 GF/W

Figures are as last publicly reported for the configuration described below, not a live measurement. Where a system was upgraded in place, the post-upgrade configuration is shown and the earlier one appears in the timeline.

What this machine is made of

One row per supplier relationship. “Supplier at build” is the company that shipped the part at the time; where that company has since been acquired, the parent it rolls up to today is shown beside it. That distinction is what makes ticker-level aggregation possible across a thirty-year dataset.

Role	Part	Supplier at build	Quantity	Confidence	Source
Integrator	- NEC SX-Aurora TSUBASA C401-8	NEC 6701TSE	-	Reported	top500.org hpci-office.jp
Accelerator	NEC SX-Aurora TSUBASA Vector Engine Accelerators NEC vector · 8C · 1.6 GHz · 16 nm · 300 W Vector Engine Type 30A 16C 1.6GHz, 8 per node, 504 nodes	NEC 6701TSE	4,032 reported	Reported	hpci-office.jp top500.org
Interconnect	NVIDIA InfiniBand NDR (Quantum-2) Interconnect Fat tree or dragonfly+ · 400 Gb/s per port · Under 0.6 microseconds Infiniband NDR200	NVIDIA NVDANASDAQ	-	Reported	top500.org hpci-office.jp

The read

The vector subsystem of Tohoku University's AOBA supercomputer, an NEC SX-Aurora TSUBASA system of 504 nodes, each with one vector host and eight Vector Engines, 4,032 in all, on InfiniBand. It was 49th on the November 2023 TOP500 and 126th in June 2026. The HPCI resource page gives service from August 2023, which is the start date used. It quotes 21.05 PFlop/s for the whole system, adding the host CPUs to the vector engines' 39.28 TFlop/s per node, while TOP500's 19.82 PFlop/s matches the vector engines alone, so the two are different scopes rather than a conflict. The host CPU model is not recorded because a Tohoku paper on the test cluster names an AMD EPYC and the HPCI page says Intel. TOP500 is the only source for Rmax, Rpeak and core count, so the tier is reported.

Timeline

2023-08 First operational source
2023-11 List debut at #49 (November 2023) source

Public list appearances

Pointers only: rank and edition, linking to the canonical entry. We do not reproduce list tables. See sourcing policy.

Site & facility

Tohoku University Cyberscience Center

Location: Sendai, Japan

top500.org

Change history

2026-09-22 Gained a Green500 rank pointer (#75 on the 2024-06 list)
2026-09-20 Added with a rank pointer on the edition where it ranked highest

Source check

We fetched this system's own citations and recorded whether each page actually mentions it. This is a corroboration signal, not a fact check, and it is published so you can see how well the sourcing holds up rather than take it on trust.

Cited source	Result	Found on the page
hpci-office.jp	names system, part and count	NEC SX-Aurora TSUBASA Vector Engine, NVIDIA InfiniBand NDR (Quantum-2) · counts: 4032
top500.org	names system and part	NEC SX-Aurora TSUBASA Vector Engine, NVIDIA InfiniBand NDR (Quantum-2)

Checked 2026-10-09 by pnpm verify. Re-run it and the table changes with the web.