i have a server with high load average, I think the problem is the raid 1.

cat /proc/mdstat  Personalities : [raid1]  md0 : active raid1 sdb1[1] sda1[0]
      256896 blocks [2/2] [UU]
       md3 : active raid1 sdb3[1] sda3[0]
      2562240 blocks [2/2] [UU]
       md4 : active raid1 sdb5[1] sda5[0]
      958566272 blocks [2/2] [UU]
       md1 : active raid1 sdb2[1] sda2[0]
      15366080 blocks [2/2] [UU]

model name : Intel(R) Core(TM)2 Duo CPU E8400 @ 3.00GHz

Linux 2.6.18-164.6.1.el5.centos.plus (local)   04/19/2010

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
          17.37    0.01    6.02   26.17    0.00   50.43

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
sda              61.09       562.65       893.73    1557214    2473546
sda1              0.01         0.27         0.02        751         42
sda2              6.11       195.50       169.78     541075     469888
sda3              0.01         0.23         0.00        641          0
sda4              0.00         0.01         0.00         18          0
sda5             54.96       366.54       723.94    1014449    2003616
sdb              54.40       433.22       893.73    1199015    2473546
sdb1              0.01         0.16         0.02        436         42
sdb2              5.31       169.00       169.78     467729     469888
sdb3              0.01         0.31         0.00        865          0
sdb4              0.00         0.00         0.00         10          0
sdb5             49.05       263.65       723.94     729695    2003616
md1              29.96       364.39       166.68    1008498     461312
md4             124.15       630.07       713.28    1743822    1974112
md3               0.05         0.43         0.00       1192          0
md0               0.04         0.32         0.00        872         10
dm-0              7.96        83.29        23.02     230530      63720
dm-1              3.67        51.81         2.73     143394       7560
dm-2              7.63        67.76        27.35     187546      75696
dm-3              8.20       134.60        14.02     372514      38792
dm-4              5.90        10.66        39.35      29498     108912
dm-5             17.39        24.52       121.79      67850     337080
dm-6             27.19       229.60       139.89     635442     387168
dm-7              0.14         1.07         0.28       2970        776
dm-8             25.84         4.23       202.89      11698     561536
dm-9             14.77         8.38       112.35      23202     310960
dm-10             5.29        12.78        29.55      35376      81784
dm-11             0.16         1.25         0.05       3450        128

the server runs lvm in the md4