Mikael Abrahamsson <swmike <at> swm.pp.se> writes: > > On Thu, 25 Jul 2013, Wes wrote: > > > Why raid10 driver from Centos 6 has a 300% slower random write performance > > (random read stays the same) than Centos 5? > > > > Please share your ideas. > > ... > Does seekmark use barriers to assure that data has actually been written? > In that case it could be that 2.6.18 has different behaviour from 2.6.32 > when it comes to barriers and that explains the speed difference. > I also made random write tests with raid1 and these return the same results on centos 5 and 6 (+/- 1%) thread 1 completed, time: 85.34, 11.72 seeks/sec, 85.3ms per request ... 93.28 total seeks per sec, 11.66 WRITE seeks per sec per thread And raid10 random write speed on centos 5 is twice as much as above - this is expected as there are 4 spindles. But centos6's raid10 (4 spindles) random write speed (~120ms/req) is even slower than 2 spindle raid1 (~80ms/req). This experiment seems to narrow the problem down to raid10. -- 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
