Largely legacy I'd say - Most new stuff is built on regular servers with Linux running - Mainframe kind of stuff would be HPC (high performing computing), thi

Largely legacy I'd say - Most new stuff is built on regular servers with Linux running - Mainframe kind of stuff would be HPC (high performing computing), this is where huge calculation are done at scale, this would be scientific/university/engineering use cases https://en.wikipedia.org/wiki/TOP500 https://en.wikipedia.org/wiki/TOP500 > most powerful non-distributed computer systems in the world.