Experimenting with Barcelona's MareNostrum 5 supercomputer

José María Cela Espín heads the department of computer applications in science and engineering at the Barcelona Supercomputing Center (BSC) in the Catalan capital. He has been working at the research center since it was still in the making, way before 2004.

The Barcelona Supercomputing Center is the national supercomputing center in Spain, and is home to MareNostrum 5, a supercomputer that can reach a peak computing power of 314 petaflops.

It is one of the most powerful computers in the world, ranking among the best 20 in the latest edition of the Top 500 supercomputer ranking. It is also part of the European High Performance Computing Joint Undertaking (EuroHPC JU) scheme. The program features several supercomputers connected across the EU.

The world's number one supercomputer is at the Lawrence Livermore National Laboratory, a federally funded research and development center in California. Its peak performance is 2,790 petaflops.

Peta means 10 to the power of 15, and flop is an abbreviation for 'floating-point operations per second.' This is the unit of measurement used to quantify a computer or a processor's computing power: how many calculations per second it can perform.

Barcelona's supercomputer can do 314 million billion calculations per second, aka 314 quadrillion, or 314,000,000,000,000,000 each second.

"With a normal computer, it will take years to complete what we do here in one hour," Cela told Catalan News. His department is divided into groups with a different research line and they work on "how to design an airplane, a car, how to introduce new fuels to reduce emissions of carbon dioxide to the atmosphere."

"With this software, we are able to simulate reality. So we can do experiments mimicking real-life conditions. We do the experiments on the computer, meaning that these experiments are faster, cheaper, and we can reproduce situations that cannot be reproduced in a laboratory," Cela explained.

The MareNostrum 5, 'Our sea' in Latin, occupies an 800-square-meter room at BSC, beside the Torre Girona church, a site built in 1857 that used to house the previous editions of the MareNostrum. It is also home to the newly unveiled first quantum computer in Spain built with 100% European technology. The supercomputer's room is equal to three tennis courts.

The research center employs almost 1,000 people, with one out of three workers foreign-born, coming from 57 different countries.

The "computer is formed by thousands of small computers like laptops at home, connected with a fast-speed network that can perform communication between them in microseconds," Cela explained.

When researchers perform large computations, they divide the work among thousands of small computers. The computer currently has 4,480 latest-generation chips, each about 8 cm2, and each chip equals the entire computing power of MareNostrum 1. A standard laptop would take 46 years to complete what the supercomputer can do in one working hour. It has the performance of 380,000 mid-range laptops.

The computers run Linux, and users can access them from their office or home, with remote access.

"You enter one of the nodes of the computer, and from there, you send the jobs to the rest of the nodes in the supercomputer," Cela explained, as the BSC is "connected to all the scientific data networks in Europe."

Despite MareNostrum 5's power, some things cannot yet be done because there is not enough computing power to simulate the problem. That is why scientists must "simplify it." However, that could lead to errors, which is why computers keep evolving to have more accurate models of reality, including boosts to focus on artificial intelligence.

BSC is open to any research group with the "single condition" that their investigation made using the supercomputer is published and cannot be kept secret.

While the MareNostrum 5 was inaugurated in December 2023, experts at BSC are already working towards MareNostrum 6. 

"Normally, a supercomputer is in the first line of computation for four years," Cela told Catalan News. "After these four years, the computer is valid, but it's not at the top of the supercomputing capacity. So it's moved to a second level of computation," he added.