On Fri, May 30, 2008 at 08:55:11AM -0400, Bill Davidsen wrote: > Justin Piszcz wrote: > > > > > >On Thu, 29 May 2008, Holger Kiehl wrote: > > > >>On Wed, 28 May 2008, Justin Piszcz wrote: > >> > >>>Hardware: > >>> > >>>1. Utilized (6) 400 gigabyte sata hard drives. > >>>2. Everything is on PCI-e (965 chipset & a 2port sata card) > >>> > >>>Used the following 'optimizations' for all tests. > >>> > >>># Set read-ahead. > >>>echo "Setting read-ahead to 64 MiB for /dev/md3" > >>>blockdev --setra 65536 /dev/md3 > >>> > >>># Set stripe-cache_size for RAID5. > >>>echo "Setting stripe_cache_size to 16 MiB for /dev/md3" > >>>echo 16384 > /sys/block/md3/md/stripe_cache_size > >>> > >>># Disable NCQ on all disks. > >>>echo "Disabling NCQ on all disks..." > >>>for i in $DISKS > >>>do > >>> echo "Disabling NCQ on $i" > >>> echo 1 > /sys/block/"$i"/device/queue_depth > >>>done > >>> > >>>Software: > >>> > >>>Kernel: 2.6.23.1 x86_64 > >>>Filesystem: XFS > >>>Mount options: defaults,noatime > >>> > >>>Results: > >>> > >>>http://home.comcast.net/~jpiszcz/raid/20080528/raid-levels.html > >>>http://home.comcast.net/~jpiszcz/raid/20080528/raid-levels.txt > >>> > >>Why is the Sequential Output (Block) for raid6 165719 and for raid5 only > >>86797? I would have thought that raid6 was always a bit slower in > >>writting > >>due to having to write double amount of parity data. > >> > >>Holger > >> > > > >RAID5 (2nd test of 3 averaged runs) & Single disk added: > >http://home.comcast.net/~jpiszcz/raid/20080528/raid-levels.html > > Other than repeating my (possibly lost) comment that this would be > vastly easier to read if the number were aligned and all had the same > number of decimal places in a single column, good stuff. For sequential > i/o the winners and losers are clear, and you can set cost and > performance to pick the winners. Seems obvious that raid-1 is the loser > for single threaded load, I suspect that it would be poor against other > levels in multithread loads, but not so much for read. On my wishlist to Justin is also what is the performance of the raid10's in degraded mode. And then I note that raid1 performs well on random seeks 702/s while the raid10,f2 (my pet) only performs 520/s - but this is on a 2.6.23 kernel without the seek performance patch for raid10,f2. I wonder if the random seeks are related to random read (and write) - it probably is, but there seems to be a difference between the results found with bonnie++ and my tests as reported on the http://linux-raid.osdl.org/index.php/Performance page. Best regards keld -- 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
