Shoubu System B

Also known as ZettaScaler-2.2 at RIKEN

Operated by RIKEN at RIKEN Wako Campus .

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: 1.06 PFlop/s
Rpeak: 1.35 PFlop/s
Rmax ÷ Rpeak: 78.5%
Cores: 953,280
Power: 60.4 kW
Per watt: 17.5 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	- ZettaScaler-2.2	ExaScaler	-	Reported	top500.org riken.jp
Accelerator	PEZY-SC2 Accelerators MIPS64 (PE array) · 2,048C · 0.7 GHz PEZY-SC2	PEZY Computing	-	Reported	top500.org riken.jp
CPU	Intel Xeon D-1571 CPUs x86-64 · 16C · 1.3 GHz · 14 nm Xeon D-1571 16C 1.3GHz	Intel INTCNASDAQ	-	Reported	top500.org
Interconnect	Mellanox InfiniBand EDR Interconnect Fat tree · 100 Gb/s per 4x port · About 0.9 microseconds Infiniband EDR	NVIDIA NVDANASDAQ	-	Reported	top500.org
Cooling	- New liquid cooling system for PEZY-SC2 system boards	ExaScaler	-	Reported	riken.jp

The read

ExaScaler ZettaScaler-2.2 system with PEZY-SC2 accelerators and Xeon D-1571 hosts on InfiniBand EDR, jointly installed at RIKEN ACCC by ExaScaler and PEZY Computing with a new liquid cooling system for the PEZY-SC2 boards. Took first place on the Green500 in November 2017, the fourth time a RIKEN machine topped that list. Appeared on the TOP500 from November 2017 (794,400 cores) to November 2018 (953,280 cores, 375th, 60.4 kW).

Timeline

2018-11 List debut at #375 (November 2018) source

Public list appearances

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

#375: TOP500, November 2018 →

Site & facility

RIKEN Wako Campus

Location: Wako, Saitama, Japan

riken.jp top500.org

Change history

2026-10-02 Added Shoubu System B, RIKEN's PEZY-SC2 ZettaScaler-2.2, 375th on the November 2018 TOP500

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
riken.jp	blocked our fetch	-
top500.org	names system and part	PEZY-SC2, Intel Xeon D-1571, Mellanox InfiniBand EDR

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