Banks and airline reservation systems tend to use vertically scaled "mainframe" architectures. In this model you need very high availability so hot-swappability

Banks and airline reservation systems tend to use vertically scaled "mainframe" architectures. In this model you need very high availability so hot-swappability is important. Linux even has hot-swap CPU support for systems like this [1]. Some IBM systems have dozens of hot-swappable hardware elements. Power supplies, CPUs, network cards, RAM, disks. [1] https://www.kernel.org/doc/html/latest/core-api/cpu_hotplug.html https://www.kernel.org/doc/html/latest/core-api/cpu_hotplug....