trouble with mysql replica and 3ware 9590 RAID controller

[Marat N.Afanasyev]

Hello!

I've encountered a trouble with very low performance of mysql replica on 
9590SE controller. as replica, mysql performs only updates and no 
selects at all, but I cannot be satisfied by performance of this 
replica, because of 100% busy of disk array with about 3-4 MBytes/s 
activity, e.g. iostat -x:

                         extended device statistics
device     r/s   w/s    kr/s    kw/s wait svc_t  %b
da0       55.5  78.9   928.1  2047.6    1 108.0  98


and more sadly, disk wait time increases sometimes to 300 seconds and more.

I've made NCQ on, changed strategy to perfom, but nothing helps. If I 
stop mysql, then I can write about 30-40 MBytes per second to this array 
(raid 1)

And I should say that this replica worked just fine on slackware with p3 
866 and IDE disks.

Mysql version is 4.0.27, twa firmware is 3.04.01.010

-- 
SY, Marat