It did not. Mach is traditional microkernel which provides IPC mechanism, process isolation and (somewhat controversially) memory mapping primitives and not muc

It did not. Mach is traditional microkernel which provides IPC mechanism, process isolation and (somewhat controversially) memory mapping primitives and not much else. In late 80's/early 90's there were various projects that attemted to build unix on top of that as true micro kernel architecture with separate servers for each system service. Performance of such design was horrible and there are two things that resulted from that that are still somewhat relevant: running whole BSD/SysV kernel as Mach task, which today means OS X and Tru64 (at the time both systems had same origin as both are implementations of OSF Unix) and just ignoring the problem which is approach taken by GNU/Hurd.