No, there is no need for the .map files to be on the player. They just need to be available, in order to figure out what died and when.

Also, it should NOT be necessary to have swap enabled to do drive copies.. but if there's a small memory leak in the copy program ("cp" ??) then it might run out of physical ram over a (did you say) 90GB copy of 10000-15000 files.. so it looks like swap on might be a good thing here (it would never be a BAD thing for cloning).

cheers