When ArchiveInOrc is on, no orc file appears and an archive.rb file exists and stays empty

[rixed]

Maybe the orc file is written only when complete though?
But then how can we include it in the stats, and how can we replay it?

This mode should only control when the .b files are turned into orc by the GC. The workers should never write directly in orc if that delays the rest of the system to use the current archive.