USA · decommissioned · classified

Cielo

Also known as Cray XE6 at Los Alamos

Operated by Los Alamos National Laboratory at Los Alamos Strategic Computing Complex .

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: 1.11 PFlop/s
Rpeak: 1.37 PFlop/s
Rmax ÷ Rpeak: 81.3%
Cores: 142,272
Power: 3.98 MW
Per watt: 0.3 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 XE6	Cray HPENYSE rolls up to Hewlett Packard Enterprise	-	Reported	top500.org
CPU	- Opteron 6136 8C 2.40GHz	AMD AMDNASDAQ	-	Reported	top500.org
Interconnect	Cray Gemini Interconnect 3D torus · About 6 GB/s per direction per link · Around 1 microsecond Cray Gemini interconnect	Cray HPENYSE rolls up to Hewlett Packard Enterprise	-	Reported	top500.org

The read

Cray XE6 for the NNSA Advanced Simulation and Computing program, run for Los Alamos and Sandia. TOP500 lists 142,272 Opteron 6136 8-core 2.4 GHz cores on the Gemini interconnect at 1.11 PFLOPS Rmax, sixth on the November 2011 list. Wikipedia describes it as the laboratory's primary system after Roadrunner's 2013 retirement, used for milestone weapons calculations, and gives 29 September 2016 as the decommissioning date; only the month is recorded. TOP500 is the only source for Rmax, Rpeak, cores and power, so the tier is reported.

Timeline

2011 First operational source
2011-11 List debut at #6 (November 2011) source
2016-09 Decommissioned source

Public list appearances

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

#6: TOP500, November 2011 →

Site & facility

Los Alamos Strategic Computing Complex

Location: Los Alamos, NM, USA
Cooling: Chilled water
Commissioned: 1993

lanl.gov

Change history

2026-10-02 Added Cielo, the LANL and Sandia Cray XE6, sixth on the November 2011 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
en.wikipedia.org	names system only	-
top500.org	names system and part	Cray Gemini

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