Okay, thanks, I'll turn it back on and try some different chunk sizes. For my own knowledge, why/what is taking place under the covers that causes this behavior? When testing with fio, it sometimes takes 1-2 minutes of "ramp up time" before the performance numbers are good/expected (when the write-intent bitmap is enabled). Thanks, Marc On Tue, Dec 22, 2015 at 9:20 PM, NeilBrown <neilb@xxxxxxxx> wrote: > On Wed, Dec 23 2015, Marc Smith wrote: > >> Solved... appears it was the write-intent bitmap that caused the >> performance issues. I discovered if I left the test running longer >> than 60 seconds, the performance would eventually climb to where I'd >> expect it. I ran 'mdadm --grow --bitmap=none /dev/md0' and now random >> write performance is high/good/stable right off the bat. > > Keeping a write-intent bitmap really is a good idea. > Using a larger bitmap chunk size can reduce the performance penalty and > preserve much of the value. It is easy enough to experiment with > different sizes. > > NeilBrown -- 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
