On Fri, 23 Dec 2016 11:24:13 -0800 Doug Dumitru <doug@xxxxxxxxxx> wrote: > With hard drives, I suspect your single disk tests are taking > advantage of the disks' on-controller cache and is doing read-ahead > and thus streaming. With the array in place, you are probably doing > 512K reads (check the array chunk size) so the disks will see bursts > of 512K reads with big gaps. The gaps are large enough that the > rotation has gone too far and the caching makes you wait a rotation. > This is just a guess. You can compensate for that via setting a higher read-ahead for the array itself, such as blockdev --setra 8192 /dev/mdX (or more) -- With respect, Roman -- 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
