On Sat, Jul 31, 2010 at 03:21:40PM +0000, Marco wrote:

quoted

quoted

sda 84.02 
sdb 113,69
md2 8,01

md2 and his meber have a very different ratio....

Strange isn't it.  And the ratios are the other-way-around to what I get.
I don't currently understand why ... but it might not be at all relevant to
the speed difference.

Hi,
i did some test on a different machine with centos 5.5 and ICH10 disk 
controller. On this machine i have no performance issue: hdparm -t return the 
same value (about 107 MB/s) on both /dev/md0 and its members

I measured the "ratio" and i obtained 8.02 for md0 and 505 for meber disk. I it 
seems that the "raito" is not so relevant for this issue. What do you think ?
In this case the md device was not mounted.
I also tried several different io scheduler whithout noting any effect on 
sequential read eprformance.

Marco

maybe try out raid10,f2 instead of raid1. You should get about double
the sequential read performance out of your raids, then, eg tested
with hdparm.

best regards
keld