[CentOS] Software RAID1 Disk I/O

Matt lm7812 at gmail.com
Tue Jan 5 22:44:44 UTC 2010


I just installed CentOS 5.4 64 bit release on a 1.9ghz CPU with 8gB of
RAM.  It has 2 Western Digital 1.5TB SATA2 drives in RAID1.

[root at server ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/md2              1.4T  1.4G  1.3T   1% /
/dev/md0               99M   19M   76M  20% /boot
tmpfs                 4.0G     0  4.0G   0% /dev/shm
[root at server ~]#

Its barebones right now.  Nothing really running.  I intended to move
our current email server over to it eventually.  The thing is slow as
mud due to disk I/O though.  I have no idea whats going on.

Here is a bit of iostat -x output.

[root at server ~]# iostat -x
Linux 2.6.18-164.9.1.el5 (server.x.us)   01/05/2010

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.13    0.10    0.03   38.23    0.00   61.51

Device:         rrqm/s   wrqm/s   r/s   w/s   rsec/s   wsec/s avgrq-sz
avgqu-sz   await  svctm  %util
sda               0.18     0.33  0.04  0.20    27.77     4.22   132.30
    3.70 15239.91 2560.21  61.91
sda1              0.00     0.00  0.00  0.00     0.34     0.00   654.72
    0.01 12358.84 3704.24   0.19
sda2              0.18     0.00  0.04  0.00    27.30     0.00   742.93
    0.30 8065.37 1930.35   7.09
sda3              0.00     0.33  0.01  0.20     0.14     4.22    21.29
    3.40 16537.41 3008.03  61.52
sdb               0.19     0.33  0.06  0.20    28.39     4.22   126.29
    2.51 9676.49 862.49  22.27
sdb1              0.00     0.00  0.00  0.00     0.34     0.00   606.29
    0.00 2202.03 643.13   0.04
sdb2              0.18     0.00  0.04  0.00    27.30     0.00   724.25
    0.10 2579.45 745.76   2.81
sdb3              0.01     0.33  0.02  0.20     0.75     4.22    22.61
    2.41 10913.16 988.40  21.74
md2               0.00     0.00  0.04  0.48     0.89     3.87     9.04
    0.00    0.00   0.00   0.00
md1               0.00     0.00  0.00  0.00     0.00     0.00     8.00
    0.00    0.00   0.00   0.00
md0               0.00     0.00  0.00  0.00     0.00     0.00     7.20
    0.00    0.00   0.00   0.00

Does anyone have an idea what I have wrong here?  This is my first
software RAID install.  Built a number of Centos servers without RAID
and they have all worked fine.

Matt


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