USA · decommissioned · classified

Sierra

Also known as ATS-2

Operated by Lawrence Livermore National Laboratory at Livermore Computing Center .

Researched with AI assistance, checked by scripts. These rows were researched by AI agents reading public operator, laboratory and vendor sources, appended by scripts and checked by automated validation; no subject-matter expert has reviewed them (how this site is made). A mechanical second-reader pass has since fetched every cited source: 1350 of 1540 systems have a readable citation that names them, and 64 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: 94.64 PFlop/s
Rpeak: 125.7 PFlop/s
Rmax ÷ Rpeak: 75.3%
Cores: 1,572,480
Power: 7.44 MW
Per watt: 12.7 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 Power System AC922	IBM IBMNYSE	-	Reported	hpc.llnl.gov olcf.ornl.gov
Accelerator	NVIDIA Tesla V100 Accelerators CUDA (Volta GV100) · 5,120C · 1.53 GHz · 12 nm · 300 W NVIDIA Volta GV100, 4 per node	NVIDIA NVDANASDAQ	17,280 reported	Reported	hpc.llnl.gov olcf.ornl.gov
CPU	IBM POWER9 22C CPUs POWER · 22C · 3.07 GHz · 14 nm · 190 W IBM POWER9 22C 3.1GHz	IBM IBMNYSE	8,640 reported	Reported	hpc.llnl.gov olcf.ornl.gov
Interconnect	Mellanox InfiniBand EDR Interconnect Fat tree · 100 Gb/s per 4x port · About 0.9 microseconds Dual-rail Mellanox EDR InfiniBand	Mellanox NVDANASDAQ rolls up to NVIDIA	-	Reported	hpc.llnl.gov olcf.ornl.gov
Storage	IBM Spectrum Scale ESS (GPFS) Storage Parallel filesystem (GPFS), erasure-coded declustered RAID · 250 PB on Summit (Alpine) · About 2.5 TB/s IBM Spectrum Scale (GPFS) at 120 PB	IBM IBMNYSE	-	Reported	hpc.llnl.gov asc.llnl.gov
Cooling	Direct-to-chip cold plate Cooling Cold plate on the package, air for the remainder · Removes roughly 50-80 percent of node heat to liquid IBM Power System AC922: water-cooled cold plates on CPU and GPU	IBM IBMNYSE	-	Reported	hpc.llnl.gov olcf.ornl.gov
Operating system	Red Hat Enterprise Linux Operating systems Linux distribution · Open source, commercial support subscription Red Hat Enterprise Linux for POWER	Red Hat IBMNYSE rolls up to IBM	-	Reported	hpc.llnl.gov olcf.ornl.gov

The read

Summit's sibling under the same CORAL procurement, with four V100s per node instead of six. The pairing is useful analytically: two systems, same vendors, same year, same fabric, different node ratios: a rare controlled comparison for anyone modelling accelerator-per-node trends. Stockpile stewardship workload.

Timeline

2014 Announced source
2018-06 List debut at #3 (June 2018) source
2018-06 First operational source
2025-09-30 Decommissioned source

Public list appearances

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

Site & facility

Livermore Computing Center

Location: Livermore, CA, USA
Cooling: Direct liquid cooling (warm water)
Commissioned: 1996

hpc.llnl.gov llnl.gov

Change history

2026-10-02 Marked Sierra decommissioned
2026-09-22 Gained a Green500 rank pointer (#62 on the 2023-11 list)

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
hpc.llnl.gov	names system only	-
olcf.ornl.gov	does not name this system	IBM POWER9 22C, Mellanox InfiniBand EDR, IBM Spectrum Scale ESS (GPFS)

Checked 2026-10-18 by pnpm verify. Re-run it and the table changes with the web.