Re: RAID5 (RAIDFrame) performance seems low.

[Ian Clark <mrrooster%gmail.com@localhost>]

On 9 April 2010 20:53, Greg Oster <oster%cs.usask.ca@localhost> wrote:
> On Fri, 9 Apr 2010 18:18:24 +0100
> Ian Clark <mrrooster%gmail.com@localhost> wrote:
>
[snip my woes]
>> dkctl raid0d addwedge dk0 $s1 $s2 ffs
>> echo Creating filesystem
>> newfs -O2 -b64k -s -64m dk0
>
> what will $s1 be in the above?  Is it going to be strip-aligned with
> the underlying RAID set?  If not, then every stripe-sized write will be
> touching two stripes, and doing two "small writes", which would result
> in abysmal performance.
>
Doh! Yes, thank you, I knew it would be something simple I'd missed!
Moving the partition to start at the apropriate point with the gpt
create worked wonders. Now seeing around 120MB/sec writes!

Thanks also to Manuel Bouyer who suggested the same thing. :)

FWIW I now get (with WAPBL turned on):-

Version 1.03c       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
thejolly.dem 16000M 127539  85 126057  33 14110   3 79853  91 134649
20 270.6   0
                    ------Sequential Create------ --------Random Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
files:max            /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
     10:65536:0/100  5415  92 +++++ +++ +++++ +++  5899  99 +++++ +++ +++++ +++
thejolly.demon.co.uk,16000M,127539,85,126057,33,14110,3,79853,91,134649,20,270.6,0,10:65536:0/100,5415,92,+++++,+++,+++++,+++,5899,99,+++++,+++,+++++,+++

This compares /very/ favourably with a friends linux box running a
RAID5 array on the same make/model of HDs!

Cheers guys!

Ian