For that case, several terabytes IIRC. It was not in-memory, that database engine was pushing records through disk storage. Obviously there were no R-trees or any other kind of slow secondary indexing; the database itself is deeply and fundamentally spatially organized, even for text and numbers data.

While there is some write amplification it is less than most databases. It only takes few disks before the scheduler can get significantly more bandwidth out of the disks than a 10GbE network has to drive that activity, so there is extra capacity. The bottleneck on most server hardware is the silicon between the storage and memory if you are doing it right.