Two Rochester-crafted supercomputers held onto their places as the second and third fastest machines in the world this week in the twice-a-year ranking as a Japanese leader picked up speed to leave them far behind.

Summit, a water-cooled IBM system that was ranked as the fastest machine in the world in 2018 and 2019, came in at #2 for the second time this year in the Top500 rankings. It was followed by Big Blue’s Sierra, which kept its third place.

The Japanese Fugaku system built by Fujitsu kept the number one spot that it first won in the June 2020 list. It increased in size and speed since the summer to hit a record-breaking 442 petaflops, more than twice Summit’s speed of 148.8 petaflops.

Much of Summit’s design, particularly its water-cooling system, came out of Rochester. Locals also orchestrated its manufacture in Guadalajara, Mexico, and its installation at the U.S. Department of Energy’s Oak Ridge National Laboratory in Oak Ridge, Tenn.

Summit first took the top spot in June 2018 with a speed of 122.3 petaflops. It reached 143.5 petaflops by November 2018 and hit the then-record-breaking speed of 148.6 petaflops in 2019.

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A petaflop is described as 1 quadrillion "floating-point" operations a second. In other words, IBM’s Summit "thinks" really, really fast, though not nearly as fast as the Fugaku system. However, it is still faster than its sibling Sierra at the Lawrence Livermore National Laboratory in California, which clocked in at 94.6 petaflops.

IBM, with the help of its now reduced Rochester campus, dominated the Top500 list in the early 2000s.

In this ranking, Big Blue’s machines accounted for just 1.8 percent of the top 500, with nine systems on the list. IBM placed 236 computers in the June 2006 ranking and 222 in November 2011.

As supercomputing hits record speeds, IBM is still remembered for its groundbreaking work that helped clear the path to this point.

A Rochester IBM system, the Roadrunner, was the first to break the long-elusive petaflop barrier on May 25, 2008. Roadrunner was "retired" or unplugged as obsolete on March 31, 2013.

After Roadrunner, IBM’s interest in supercomputers dwindled and rolled to a halt.

However, that changed in 2013, when IBM won a $325 million federal contract to build Summit and Sierra for CORAL, a collaboration between the U.S. Department of Energy, the National Nuclear Security Administration and the Office of Science.