On Wed, 28 May 2008, Justin Piszcz wrote:

quoted text
> 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

--
unsubscribe notice
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/