Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx> wrote: > I have a question, when I use multiple writer threads (2 or 3) I > see 550-600 MiB/s write speed (vmstat) but when using only 1 thread, > ~420-430 MiB/s... It's called scheduling buffer flushes, as well as the buffering itself. > Also without tweaking, SW RAID is very slow (180-200 > MiB/s) using the same disks. But how much of that tweaking is actually just buffering? That's a continued theme (and issue). Unless you can force completely synchronous writes, you honestly don't know. Using a larger size than memory is not anywhere near the same. Plus it makes software RAID utterly n/a in comparison to hardware RAID, where the driver is waiting until the commit to actual NVRAM or disc is complete. -- Bryan J. Smith Professional, Technical Annoyance b.j.smith@xxxxxxxx http://thebs413.blogspot.com -------------------------------------------------- Fission Power: An Inconvenient Solution - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
