Manuel Bouyer wrote:

> Ok, could you try to limit your IDE disks to UDMA mode 2 instead of 4 ?
> This is with 'flags 0xa00' for each of your wd entries in kernel config file.
> 
> I'm not conviced I got the VIA Ultra66 stuff rigth :(
> 

Ok i tried ...... without results:(

Anyway,the UDMA/66 supports seems to perform good without RAID-5

Maybe a simple mis-configuration of raid device?

I mean ,using a wrong stripe size may lead to such loss of performance?
 
> You may want something larger than 32 here, This mean 16k blocks read/write to
> the disk. You'd want something larger - 64 or 128 - to decrease the interrupt
> load and increase the IDE bandwith.
> The effect of this can be more important at Ultra/66 than Ultra/33.

As far as i can see there'is not agreement about correct stripe size.
Anyone has its own idea about the 'right way' do to it .
So i think is better try every reasonable value (16 to 64),but this may
take a long
time :(

Any suggestion is welcome.

Bye!