This is server1: working great.

[root@mx1 /]# iostat
Linux 2.6.9-11.ELsmp      11/21/2005

avg-cpu:  %user   %nice    %sys %iowait   %idle
           8.29    0.01    2.35    0.71   88.63

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
sda              53.03        21.35       923.22   78593914 3398126118

[root@mx1 /]# vmstat
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa
 3  0   6284 104220  40660 184872    0    0     5     3    3     2  8  2 89  1

================================================================================

This is machine2:

[root@mx3 tmp]# iostat
Linux 2.6.9-22.0.1.ELsmp     11/21/2005

avg-cpu:  %user   %nice    %sys %iowait   %idle
          14.27    0.00    4.64   57.08   24.01

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
sda             131.18      2271.35      1132.00    3734281    1861102

[root@mx3 tmp]# vmstat
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy id wa
 0 10 152008 470212    892  25168  716   97  1137   565 1253   419 14  5 24 57

[root@mx3 tmp]# sar
10:29:11 AM       LINUX RESTART

10:30:02 AM       CPU     %user     %nice   %system   %iowait     %idle
10:40:19 AM       all     11.28      0.00      3.68     81.72      3.31
10:50:01 AM       all     17.22      0.00      5.52     39.15     38.11
Average:          all     14.17      0.00      4.57     61.07     20.19

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Both servers runs sendmail+mailscanner