On Thu, Dec 03, 2015 at 07:43:10PM +0100, Petar Bogdanovic wrote: > On Wed, Dec 02, 2015 at 08:23:28PM +0000, Michael van Elst wrote: > > > > That's probably why setting the queues all to fcfs is the best > > for you. > > Not as dramatic as Emile's numbers but significantly higher read > throughput:
What strategy are you using to sort inside RAIDframe? This is a property of the RAID set; you can see it with raidctl I believe for autoconfigured sets. I wouldn't be terribly surprised to see bad interactions between priocscan and RAIDframe's scan or cscan strategies. What about the "fifo" strategy? It's important, though, to understand that there are *very* few pure bulk read applications in this world (except single-stream video) and very few pure bulk write applications except database logs. That means that single-stream pure read or write tests are really pretty awful predictors of disk performance for real workloads. The "priocscan" strategy, in particular, limits pure read/pure write performance *by design* in order to achieve lower latency under real world mixed workloads. I would not be so quick to discard it -- though I would not use it on something like an SSD, and I am skeptical it would perform well when stacked on one of RAIDframe's elevator-sort variants. Thor
