Re: RAID5 (RAIDFrame) performance seems low.

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Fri, Apr 09, 2010 at 06:18:24PM +0100, Ian Clark wrote:
> Hi All,
> 
> I've had a 4 disc RAID5 (RAIDFrame) array for a couple of years now which
> has good read performance, but not great write performance, which I always
> put down to not doing my reading beforehand and having an array that wasn't
> (n+1) drives, where n is a power of 2, allowing matching FS block size to
> stripe size. This array was 4x500G Hitachi 7K1000 consumer level SATA
> drives.
> 
> Anywhoo, time has passed and it's time to replace the array with something a
> little larger, so this time I've gone for 3x2T HGST 7K2000 drives, however
> despite hoping for better write performance it's looking sofar to be much
> much worse, and I was wondering if anyone can suggest something I may have
> missed, or it really should be that slow.
> 
> (ian:~)$ cat doraid.sh
> #!/usr/local/bin/bash
> 
> label=`date +%Y%m%d%H%M`
> echo Erasing raid
> raidctl -uv raid0
> echo Creating raid
> raidctl -C raid0.conf raid0
> echo Labeling raid $label
> raidctl -I $label raid0
> echo Parity rewrite
> raidctl -iv raid0
> echo Destroying GPT
> gpt destroy raid0
> echo Creating new GPT
> gpt create raid0
> echo Adding ufs partition
> sizes=`gpt add -tufs raid0 2>&1| grep dkctl | sed
> "s/.*addwedge.......\([^<]*\).*/\1/"`
> s1=`echo $sizes | cut -f1 -d' '`
> s2=`echo $sizes | cut -f2 -d' '`
> echo Creating wedges
> dkctl raid0d delwedge dk0
> echo dkctl raid0d addwedge dk0 $s1 $s2 ffs
> dkctl raid0d addwedge dk0 $s1 $s2 ffs
> echo Creating filesystem

What parameters does this give you for the wedge ?

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--