Migrating tasks from “Phoenix” to “Piz Daint” took place gradually over two years. Only at the end of 2017, when enough comparative data was available to make an informed decision, did CSCS and CHIPP decide to use “Piz Daint” for future data analysis. “Piz Daint” has been used actively for simulation and data analysis in LHC experiments since April 2018. In April 2019, the transfer will finally be complete and “Phoenix” will be decommissioned. Meanwhile, the project participants have succeeded in testing the externalization of the Tier 0 system onto “Piz Daint” and have provided CERN with direct computing capacity for highly complex data processing. The project participants look back at what they have achieved with a certain degree of awe: “The project was far more complex to manage than any technical limitation or problem we have had so far,” says Miguel Gila, HPC System Engineer at CSCS.

More work on the project to come

The comparison between “Piz Daint” and “Phoenix” has shown that both systems perform their functions with similar efficiency, but “Piz Daint” is slightly more cost-effective. According to the project participants, however, the CHIPP community will use only the computer nodes consisting of two CPUs for the time being, and not all the full benefits of “Piz Daint”. In future, it may be possible to use hybrid computer nodes consisting of one CPU and one GPU to run calculations much more efficiently. A big advantage for the researchers is that they can tap into much more computing power at short notice – at the “push of a button” – if needed.

The current upgrade of the LHC to the High-Luminosity LHC, which will be online from 2025 to 2034 and enable breakthroughs in particle physics, requires up to 50 times more computing power for data analysis and simulations. However, the high energy physicists predict that with the current computing models, a significant shortfall of resources will occur. This will require various software and hardware optimisations. Since HPC systems such as “Piz Daint” already have optimised hardware, the researchers are confident that it will be possible to make savings. They expect the project to serve as a model for WLCG, as it has opened doors, for instance, in terms of new computing models and software optimisation.

Source: CSCS