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High IO and Load Issues

Discussion in 'Workarounds and Optimization' started by Binhex, Nov 5, 2010.

  1. Binhex

    Binhex Registered

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    I have a cPanel server running on an IBM x3650 server, it is using a raid 6 configuration with 2 logical partitions and 12GB of memory. The server has approximately 550 sites on it at the moment.

    The issue is IO wait time is excessively high and I believe therefore pushing the load on the box as well. Below is an example from "sar":

    07:50:01 AM all 0.63 0.06 0.61 13.61 0.00 85.09
    08:00:01 AM all 0.50 0.00 0.27 7.60 0.00 91.63
    08:10:01 AM all 0.74 0.11 0.50 14.87 0.00 83.79
    08:20:01 AM all 1.02 0.05 0.53 12.12 0.00 86.29
    08:30:01 AM all 0.95 0.00 0.50 11.92 0.00 86.63
    08:40:01 AM all 1.95 0.00 0.63 13.13 0.00 84.28
    08:50:09 AM all 1.19 0.17 0.87 24.11 0.00 73.66
    09:00:01 AM all 0.94 0.05 0.49 15.98 0.00 82.54
    09:10:01 AM all 1.22 0.03 0.47 14.39 0.00 83.89
    09:20:05 AM all 0.90 0.00 0.47 12.20 0.00 86.42
    09:30:01 AM all 0.95 0.02 0.46 12.08 0.00 86.49
    09:40:01 AM all 0.77 0.00 0.38 10.17 0.00 88.67
    09:50:01 AM all 1.01 0.04 0.52 15.77 0.00 82.67
    10:00:01 AM all 0.91 0.01 0.45 10.37 0.00 88.27
    10:10:01 AM all 0.82 0.00 0.40 12.51 0.00 86.27
    10:20:12 AM all 1.23 0.04 0.63 17.96 0.00 80.15
    10:30:01 AM all 1.09 0.00 0.42 10.93 0.00 87.56
    10:40:01 AM all 0.74 0.04 0.40 13.10 0.00 85.71
    10:50:01 AM all 0.70 0.00 0.38 10.79 0.00 88.12
    11:00:01 AM all 0.86 0.04 0.55 19.04 0.00 79.51

    11:00:01 AM CPU %user %nice %system %iowait %steal %idle
    11:10:01 AM all 1.22 0.03 0.50 19.28 0.00 78.97
    Average: all 0.76 0.03 0.34 6.70 0.00 92.18

    Output from TOP:

    top - 11:41:31 up 2 days, 11:29, 4 users, load average: 2.79, 4.51, 6.16
    Tasks: 338 total, 1 running, 336 sleeping, 0 stopped, 1 zombie
    Cpu(s): 1.6%us, 0.5%sy, 0.0%ni, 97.4%id, 0.4%wa, 0.0%hi, 0.0%si, 0.0%st
    Mem: 12299608k total, 12073712k used, 225896k free, 941560k buffers
    Swap: 12281684k total, 172k used, 12281512k free, 8724168k cached

    We are running the latest version of cPanel on CentOS 5.5. Given the type of configuration for the box, can anyone think of something that could be the issue in cPanel or otherwise driving the very high IO?
     
    #1 Binhex, Nov 5, 2010
    Last edited: Nov 5, 2010
  2. johnburk

    johnburk Well-Known Member

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    You are using 12Gb of the 12GB. Is there any disk-cache beeing used by one or more of the 550 websites?
     
  3. cPanelTristan

    cPanelTristan Quality Assurance Analyst
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    Is the 2.79 an example of the high load? Because 2-3 isn't a high load on a box with 550 sites on it. It would be preferable to show the top processes running and load when it's actually high. Also, the I/O isn't high in that top return:

    Cpu(s): 1.6%us, 0.5%sy, 0.0%ni, 97.4%id, 0.4%wa, 0.0%hi, 0.0%si, 0.0%st

    This is 0.4% iowait with 97.4% idle here.
     
  4. syslint

    syslint Well-Known Member

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    Hello,
    What type of HDD are you using , Is it SAS or SATA . because you say seeing lot of I/O issues.
     
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