El Capitan, The World’s Fastest Supercomputer, Goes Live in California

The El Capitan supercomputer runs on the "Tri-Lab Operating System Software" (TOSS), a custom operating system developed specifically for the National Nuclear Security Administration's (NNSA) "Tri-Labs" which includes Lawrence Livermore National Laboratory, Los Alamos National Laboratory, and Sandia National Laboratories; essentially, it's a customized Linux distribution tailored to their needs