Supercomputers/Systems/KEK SAKURA
Japan · operational · hpc
KEK SAKURA
Also known as SAKURA Blue Gene/Q; KEK Blue Gene/Q System B
Operated by KEK at KEK Tsukuba 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
- 536.66 TFlop/s
- Rpeak
- 629.15 TFlop/s
- Rmax ÷ Rpeak
- 85.3%
- Cores
- 49,152
- Power
- 246.56 kW
- Per watt
- 2.2 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 | - IBM Blue Gene/Q system supplied by IBM | IBM | - | Reported | top500.org |
| CPU | IBM PowerPC A2 (Power BQC) CPUs PowerPC A2 · 18C · 1.6 GHz · 45 nm · 55 W IBM Power BQC 16C 1.6GHz processors | IBM | - | Reported | top500.org |
| Interconnect | IBM BlueGene/Q 5D torus Interconnect 5D torus · 2 GB/s per link per direction Blue Gene/Q custom 5D torus interconnect | IBM | - | Reported | top500.org |
The read
One half of the IBM Blue Gene/Q installed at KEK in 2012 as System B of its supercomputer system. KEK describes System B as 1.26 PFlop/s peak in total; the TOP500 lists it as two 629 TFlop/s machines, SAKURA and HIMAWARI, and only SAKURA is recorded here. SAKURA entered the TOP500 at 36th in June 2012 and was last listed in June 2017.
Timeline
Public list appearances
Pointers only: rank and edition, linking to the canonical entry. We do not reproduce list tables. See sourcing policy.
Site & facility
Change history
- 2026-10-07 Added KEK SAKURA
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 |
|---|---|---|
| indico.cern.ch | does not name this system | - |
| top500.org | names system and part | IBM BlueGene/Q 5D torus |
Checked 2026-10-09 by pnpm verify. Re-run it and the table changes with the web.
Further reading
Operating a supercomputer
Acceptance testing, why "installed" and "in production" are six months apart, and the machine lifecycle.
Inside a node
Latency-optimised versus throughput-optimised processors, NUMA, and the end of the host-to-device copy.
The interconnect
Topologies, why latency and tail behaviour matter more than bandwidth, and how the fabric market consolidated.