27.06.2013 03:25, Nicholas A. Bellinger wrote: > On Wed, 2013-06-26 at 12:55 +0300, Vladislav Bogdanov wrote: >> 26.06.2013 11:48, Nicholas A. Bellinger wrote: >>> Hi Vladislav, >>> >>> On Mon, 2013-06-24 at 18:18 +0300, Vladislav Bogdanov wrote: >>>> Hi, >>>> >>>> I'm evaluating performance of different targets (actually LIO and IET) >>>> on top of RAID5 >>>> (mdraid) for my customer. >>>> ... >> But, again, IET magically does the trick - 85Mb/s is very close to both >> wire speed and to >> expected maximal raid5 write speed when IO size is equal to stripe size, >> so writing the >> full stripe costs only 4 IOs (2 reads and 2 writes). >> > > Ok, this sounds more and more like FUA WRITEs are forcing write-through, > and generating partial stripe writes to occur. > > Can you disable emulate_fua_write=0 following the above and retry..? Yep, that helped, thank you very much! Vladislav -- To unsubscribe from this list: send the line "unsubscribe target-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
