Snow (supercomputer)


July 6, 2022

Lumi (English: Large Unified Modern Infrastructure) is a supercomputer located in CSC's data center in Kajaani. It was put into use in June 2022, when it became the fastest supercomputer in Europe and the third fastest in the world. The theoretical peak power of the computer was initially estimated to be more than 200 petaflops, or 200 × 1015 floating-point calculations per second. Later, the theoretical peak power of the computer is said to be more than 550 petaflops, which exceeds the 415.5 petaflops achieved by Fugaku of the RIKEN Institute. The computer uses new technology, which increased its performance. In May 2022, the computer rose to third place on the TOP500 list of supercomputers and is the largest and fastest computer in Europe with a High-Performance Linpack (HPL) result of 151.9 petaflops. The LUMI-G partition on the computer was not yet fully installed at the time of the result. The speed of the machine will double during the summer of 2022, and the device will operate at full power from early autumn. The device was delivered by Hewlett Packard Enterprise, and it is owned by the European Union joint venture EuroHPC. The machine is hosted by CSC.


In October 2020, it was reported that Hewlett Packard Enterprise (HPE) had been awarded the purchase of a computer financed by the European EuroHPC project. The computer was said to start operating in 2021 and reach its full capacity in 2022. Delays in deployment are due to global supply chain delays in the semiconductor industry. The first pilot phase ended at the end of 2021, followed by the installations of the second phase. Lumi was officially commissioned on June 13, 2022. Its life cycle ends in 2027 at the latest.


EuroHPC's budget for the years 2019–2020 was more than 960 million euros, of which more than 200 million euros is for the Lumi computer. The share of the computer itself is 145 million euros. Part of the funding comes from the EU and the countries of the Lumi consortium, which includes ten European countries (Belgium, Czech Republic, Denmark, Estonia, Finland, Iceland, Norway, Poland, Sweden and Switzerland).

Environmental Effects

The system is completely powered by electricity produced by hydropower, and with the use of waste heat, the carbon footprint is either zero or negative. The waste heat produced by the Lumi computer makes up one fifth of Kajaani's district heating.


Lumi is based on Hewlett Packard Enterprise's Cray EX supercomputer. The computer has around 200,000 AMD Epyc CPU cores, 32 terabytes of RAM and AMD Instinct graphics processors (MI250X). Epyc processors use the Zen 3 architecture and are connected with the NUMA architecture. The system uses Ceph and Luster file systems. The system has 30 petabytes of encrypted storage, 7 petabytes of fast storage using Flash memory for short-term storage, and an 80 petabytes storage system. The computer uses a Cray Slingshot switching network. The system has OpenShift/Kubernetes support for microservices. As part of system development, program code is transferred from Nvidia's V100 processors (CUDA) to AMD's processors (HIP, ROCm). Heterogeneous-Computing Interface for Portability (HIP) enables the same program code to be compiled for both AMD and Nvidia platforms. The system consists of sections, of which LUMI-C contains only nodes containing Epyc processors and LUMI-G contains graphics processors. LUMI-F contains Flash storage, LUMI-O and LUMI-P other storage. LUMI-K is a container service for cloud service and LUMI-D for data analysis. The machine is located in a computer room built in the hall of a former paper factory. The conference hall is surrounded by a white, illuminated protective shell made of aluminum composite, the shape of which symbolizes a snow cone. The shell is used in the marketing of the machine.