Data center of PAL-XFEL

A data center is indispensable to experimental light source facilities to provide scientists with both real-time and offline computing capabilities to analyze, store, and archive the data generated at the beamlines. This paper describes the Pohang Accelerator Laboratory (PAL) computing facility built to support the X-ray Free Electron Laser (XFEL). PAL designed the data center for its XFEL in 2014 and built it in 2015. Some components of the design were driven by lessons learned at the Linac Coherent Light Source (LCLS) XFEL at the SLAC National Accelerator Laboratory. The data center has evolved through three iterations since 2015 and PAL is now planning a fourth upgrade. The storage capacity has increased from 200 TB in 2015 to 1.3 PB in 2019, and 6.9 PB in 2022. On the other hand, PAL has not added servers for computing nodes since the first deployment. PAL plans to add a new 15 PB storage system and a 30 PB tape library as well as servers for computing nodes and basic services after 2024.