Hi keld, Thanks for the reply. On Thu, May 30, 2019 at 12:04:20PM +0200, keld@xxxxxxxxxx wrote: > you need to clarify which layout you use with md raid10. I did not bother as I included the commands for the array setup which should indicate that default layout was used. > the layouts are near, far and offset, with very different performance characteristics. I did not think these would be of any interest on SSD/NVMe which is my main concern and is the area where RAID-1 outperforms RAID-1 by a factor of 3 for 100% 4KiB random reads. > far and offset are designed to be faster than near, which I understand that you use. > So why are you using the slowest md raid10 layout, and not mentioning this fact? Because I did not see the point of a non-default layout for fast flash devices. > maybe you could run your tests for all 3 layouts? Yes I will be happy to do this and see what happens but I'm not optimistic that it will change matters so that RAID-10 is able to direct most reads to the fastest half. Still it may be interesting by itself if it does have some effect even on SSD/NVMe. Cheers, Andy
