Supercomputers/Systems/SahasraT
India · operational · hpc
SahasraT
Also known as SERC Cray XC40; IISc SERC Supercomputer
Operated by IISc at IISc Bengaluru .
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
- 901.51 TFlop/s
- Rpeak
- 1.24 PFlop/s
- Rmax ÷ Rpeak
- 72.5%
- Cores
- 31,104
- Power
- 607.5 kW
- Per watt
- 1.5 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 | - Cray XC40 | Cray HPENYSE
rolls up to Hewlett Packard Enterprise | - | Verified | top500.orgiitg.ac.in |
| CPU | - Intel Xeon E5-2680v3 12C 2.5GHz | Intel | - | Reported | top500.org |
| Interconnect | Cray Aries Interconnect Dragonfly · About 10 GB/s per direction · Around 1 microsecond Cray Aries interconnect | Cray HPENYSE
rolls up to Hewlett Packard Enterprise | - | Reported | top500.org |
| Operating system | Cray Linux Environment Operating systems Linux, Cray-customised · Proprietary layer over open-source Linux Cray Linux Environment | Cray HPENYSE
rolls up to Hewlett Packard Enterprise | - | Reported | top500.org |
The read
Cray XC40 at the Supercomputer Education and Research Centre of the Indian Institute of Science, long described as the most powerful machine in India. TOP500 lists a Cray XC40 with Xeon E5-2680v3 12C 2.5GHz processors on the Aries interconnect, 31,104 cores, Rmax 901.5 TFlop/s, Rpeak 1,244.16 TFlop/s and 607.5 kW; it debuted at rank 79 on the June 2015 list and last appeared at rank 488 in November 2018, which is the status date used here. IIT Guwahati's HPC page independently lists it at 1,244.2 TFlop/s peak with about 33,000 cores (a rounder, system-level count).
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
- 2026-10-02 Added SahasraT, IISc SERC Cray XC40, 79th on the June 2015 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 |
|---|---|---|
| top500.org | does not name this system | Cray Aries, Cray Linux Environment |
| iitg.ac.in | names system only | - |
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.