> Depends is the best answer. It really depends on LVM and the other block > layer devices. As the io requests descend down the different layers they > will enter multiple request_queues, each request_queue will have and io > scheduler assigned to it, either the system default or one of the > others, or one of the block devices own, so it is hard to say. Only by > testing can you know for sure. In my tests LVM is very good with > unnoticeable overhead going to hardware RAID, but if you use MD RAID > then your experience might be different. > Hope this helps clarify. It does, and I should have specified at the outset that this was with respect to hardware raid. -- During times of universal deceit, telling the truth becomes a revolutionary act. George Orwell