On Jan 11, 2010, at 8:21 PM, bank kus wrote: >> resource management policies implemented. By default, >> ZFS will queue >> 35 I/Os to each leaf vdev, so it is not clear that >> scheduling above the ZFS >> level will be as effective > > It doesnt have to be above the _ZFS_ layer no? In place of a single queue one > could maintain separate queues that are either timesliced between or FSSed > (some form of ticket scheduling where ticket = priority * age) You could > still have elevator + deadline and therefore not hurt disk bandwidth.
I think if you look at the majority of performance problems reported on this forum, they are latency and not bandwidth bound. Modern systems tend to be over provisioned for bandwidth. -- richard
