The osm2city worldbuild is an attempt by merspieler started in May 2019 of providing global coverage with osm2city scenery.
Since I was disappointed by the information I could get on the world scenery 2.0 build, espectailly on the machine it run on, I've decided to give some insight, on what is needed to run an osm2city worldbuild.
As of January 2020 the build is run on a server with two 8-core/16-thread CPUs and 96GB RAM. While at first the CPU seems to be the bottleneck, once you get into densly packed areas the RAM becomes the limiting factor. I've seen a single thread taking up more than 80GB of RAM and even caused out-of-memory problems on this server. As a general rule, watch how much RAM is currently used and adjust the number of running processes accordingly.
For storage I've started with five 4TB HDDs configured in a RAIDZ2 with an effective capacity of just below 12TB but changed to RAID10 (with one spare drive, about 8TB effective) to improve IO performance. Currently 8TB this is more than is needed. As of writing the global osm data in the database has a size of 2.3TB but this requirement can be lowered (with a penalty in runtime) by only importing the required area from the highly compressed .osm.pbf file. With this approach, the initial try worked relativly well on a 1TB HDD with enough headroom. There are quite a number of random IOPS which causes some IO wait time, up to 80% of the CPU on my Server so an SSD would certainly benificial for some of the data or as L2ARC.