Re: Performance Characteristics of All Linux RAIDs(mdadm/bonnie++)

[Justin Piszcz]

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
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