Sierra Early Access: In late 2016, LLNL acquired three small-scale “early access” (EA) versions of Sierra, consisting of IBM Minsky compute nodes with 20 Power 8 cores each and 4 NVIDIA Pascal graphics processing unites (GPUs). These small systems featured components only one generation behind those of Sierra. EA systems enabled application porting and tuning in advance of the CORAL Sierra system delivery and acceptance, employing beta software co-designed by the CORAL laboratories and IBM.
Sierra: This high performance computing (HPC) system came online in 2018, and was decommissioned in September 2025. ASC Program scientists and engineers used Sierra to assess the performance of nuclear weapon systems as well as nuclear weapon science and engineering calculations. These calculations are necessary to understand key issues of physics, the knowledge of which later makes its way into the integrated design codes. The IBM-built Sierra supercomputer provided over six times the sustained throughput performance and over five times the sustained scalable science performance of its predecessor, Sequoia, with a 125 petaFLOP/s peak. Sierra, which combined two types of processor chips—IBM’s Power 9 processors and NVIDIA’s Volta graphics processing units, was over five times more power efficient than Sequoia, with a peak power consumption of approximately 11 megawatts. This system was sometimes called Sierra ATS to distinguish it from an earlier, smaller machine. For more information about the history of Sierra's procurement, see the CORAL/Sierra Procurement page.
