Hard Disk utilization
 

Hello,

I have dedicated server running CentOS + MySQL server. I am using this server from last 3 years. It is quite a busy server and have a lot reads and writes (only MySQL activity). From last some days MySQL performance has been decreased. Today I ran the iostat command and got the below results. I do not know about these things, can someone guide me and tell me whether should I replace server/hard disk or not?

$ iostat -d -x 5 3
Linux 2.4.21-47.0.1.ELsmp (server.com.com) 07/08/2008

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util
sda 5.19 40.74 13.19 54.91 29.26 59.45 14.63 29.73 1.30 0.00 0.01 0.02 0.11
sda1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 3.69 0.00 58.12 37.98 0.00
sda2 0.34 0.75 0.40 0.45 5.88 9.69 2.94 4.84 18.26 0.00 1.77 0.37 0.03
sda3 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 18.13 0.00 22.68 6.48 0.00
sda4 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2.00 0.00 0.00 0.00 0.00
sda5 0.14 0.40 0.10 0.36 1.91 6.14 0.96 3.07 17.49 0.00 2.24 0.89 0.04
sda6 0.00 0.08 0.00 0.04 0.00 0.93 0.00 0.47 24.39 0.00 0.81 24.72 0.09
sda7 0.01 0.45 0.05 0.23 0.44 5.57 0.22 2.78 21.50 0.00 2.33 1.32 0.04
sda8 4.70 39.06 12.64 53.82 21.02 37.12 10.51 18.56 0.87 0.00 0.02 0.01 0.07
hda 0.06 0.00 0.00 0.00 0.12 0.00 0.06 0.00 70.35 0.00 24.95 3.56 0.00
hda1 0.06 0.00 0.00 0.00 0.12 0.00 0.06 0.00 70.36 0.00 24.95 3.56 0.00

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 99.20 0.40 150.50 3.21 1999.20 1.60 999.60 13.27 2.17 14.36 6.59 99.40
sda1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sda2 0.00 0.80 0.00 0.40 0.00 9.62 0.00 4.81 24.00 0.01 30.00 30.00 1.20
sda3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sda4 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sda5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sda6 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sda7 0.00 1.20 0.00 0.40 0.00 12.83 0.00 6.41 32.00 0.01 20.00 20.00 0.80
sda8 0.00 97.19 0.40 149.70 3.21 1976.75 1.60 988.38 13.19 2.15 14.30 6.62 99.40
hda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
hda1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s avgrq-sz avgqu-sz await svctm %util
sda 0.00 112.60 0.20 148.60 1.60 2123.20 0.80 1061.60 14.28 2.32 14.41 6.65 99.00
sda1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sda2 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sda3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sda4 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sda5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sda6 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sda7 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
sda8 0.00 112.60 0.20 148.60 1.60 2123.20 0.80 1061.60 14.28 2.32 14.41 6.65 99.00
hda 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
hda1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

All of your hard disk activity is in partition sda8 on hard drive sda. Hard drive hda is barely used. The best way to speed up MySQL is to rearrange the files in sda8 so that half of the MySQL hard drive activity is on hda and half is on sda.

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Steve Stites