Supercomputers/Systems/T2K Todai
Japan · operational · hpc
T2K Todai
Also known as T2K Open Supercomputer (Todai Combined Cluster); HA8000-tc/RS425
Operated by University of Tokyo at University of Tokyo Computer Centre .
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: 1263 of 1345 systems have a readable citation that names them, and 56 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
- 82.98 TFlop/s
- Rpeak
- 113.05 TFlop/s
- Rmax ÷ Rpeak
- 73.4%
- Cores
- 12,288
- Power
- 638 kW
- Per watt
- 0.1 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 | - Hitachi HA8000-tc/RS425 cluster, 952 nodes | Hitachi | - | Reported | cc.u-tokyo.ac.jptop500.org |
| CPU | - AMD quad-core Opteron 2.3 GHz, four per node, 952 nodes | AMD | - | Reported | cc.u-tokyo.ac.jptop500.org |
| Interconnect | - Myrinet 10G | Myricom | - | Reported | top500.org |
| Storage | - Hitachi disk system of 1 PB capacity | Hitachi | - | Reported | cc.u-tokyo.ac.jp |
The read
The University of Tokyo member of the T2K alliance: 952 nodes of Hitachi HA8000-tc/RS425, each with four quad-core 2.3 GHz Opterons, 140 TFlop/s peak, 32 TB of memory and a 1 PB disk system, on Myrinet 10G. The university's own 2 June 2008 symposium slides give a measured Linpack of 82.9842 TFlop/s on 768 nodes against a 113 TFlop/s peak (73.4 percent efficiency), which is exactly the 82.98 and 113.05 TFlop/s TOP500 records for 12,288 cores (https://www.top500.org/system/175564/, 17th in June 2008). Later lists show a larger configuration, 15,104 cores, 101.74 TFlop/s Rmax and 138.96 TFlop/s Rpeak (https://www.top500.org/system/176723/), still listed in June 2013. The row keeps the 2008 configuration the slides confirm. The shutdown date is not stated, so status is recorded as of the last list.
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
- 2026-10-09 Added T2K Todai
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 |
|---|---|---|
| cc.u-tokyo.ac.jp | does not name this system | - |
| top500.org | names system only | - |
Checked 2026-10-13 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.