Hi NeilBrown, As you may already see, I run a lot of tests with 10 HDDs for the patchset "simplify block layer based on immutable biovecs" Here is the summary. http://minggr.net/pub/20150608/fio_results/summary.log MD RAID6 read performance is OK. But write performance is much lower than HW RAID6. Is it a known issue? Thanks. -- 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