Lassen significantly increases the computing power available to ASC and M&IC researchers on the open network.
Greg Tomaschke, M&IC Deputy Director
Lassen supercomputer at LLNL


Lassen is similar to the classified Sierra system (same architecture) but smaller in size: ~20 petaFLOP/s peak performance compared to Sierra’s 125 petaFLOP/s peak. The system is designated for unclassified simulation and analysis.

Lassen was part of the contract that brought Sierra to Livermore, and it debuted in 2018 at No. 11 on the TOP500 List, one spot behind LLNL’s Sequoia. Lassen is shared by the Multiprogrammatic and Institutional Computing (M&IC) and Advanced Simulation and Computing (ASC) programs.

Processor Architecture

IBM Power and NVIDIA Volta processors

Operating System


Processor Clock Rate/Process Clock Speed

3.4 GHz



Cores per Node


Total Cores


Memory per Node

320 GiB

Total Memory

213,120 GB