Re: SW-RAID0 Performance problems

["Jakob Østergaard" <jakob@unthought.net>]

On Fri, Apr 13, 2001 at 01:47:30PM +0200, Andreas Peter wrote:
> Hi,
> I've successfully set up SW-RAID0 with Kernel 2.4.3 and Raidtools 0.9.
> I did this to increase the performance of my HD, but nothig happens.
> The hdparm results:
> hdparm -t /dev/md0 : 20.25 MB/sec
> hdparm -t /dev/hda : 20.51 MB/sec
> hdaprm -t /dev/hdc : 20.71 MB/sec
> 
> I thougt the performnace of RAID0 should near 40MB/sec.
> I played with different chunk-sizes, but the result was everytime the same.
> The drives are both Maxtor DiamondMax VL40, 30GB, DMA on. 
> No other drive is attached on the bus.
> 
> Here are also some bonnie++ results:
...

I can't say much about this... It looks like your setup is perfectly allright,
and the performance *should* go up.   Instead it looks like you get a small
performance drop from using the RAID.   Most odd.

Do you have more controllers in the machine ? If so could you try to move eg.
hdc to the second controller ?  The only thing I can imagine being the cause of
the poor performance is, if your controller somehow doesn't handle both
channels very well simultaneously.   It's far fetched, but it's the only
suggestion I can think of.

Maybe Andre has comments ?

I usually get a good speedup from using RAID-0 on 2.4.3 with IDE.  Both with
two disks and with six.   This is with Intel PIIX4 and Promise 20262
controllers.

-- 
................................................................
:   jakob@unthought.net   : And I see the elder races,         :
:.........................: putrid forms of man                :
:   Jakob Østergaard      : See him rise and claim the earth,  :
:        OZ9ABN           : his downfall is at hand.           :
:.........................:............{Konkhra}...............: