Messages in this thread | | | Date | Thu, 29 May 2008 06:44:13 +0000 (GMT) | From | Holger Kiehl <> | Subject | Re: Performance Characteristics of All Linux RAIDs (mdadm/bonnie++) |
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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
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