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Disk i/o issue - kjournald

Discussion in 'Workarounds and Optimization' started by MarkPW, Mar 29, 2013.

  1. MarkPW

    MarkPW Member

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    I'm having a problem with disk i/o on my web server - 2 x Harpertown 5410, 4G RAM, 2x750G SATA2, hardware RAID 1, CentOS 4.5/cPanel.

    I've found that kjournald is the culprit causing disk util to average over 90%. However, I can't see exactly what it's writing and why it's writing so much. The problem seems to have started since upgrading PHP to 5.3 so I thought it might have been a log associated with that, but having checked everything and even turning off access logs and domlogs completely, it's made next to no difference. What I can't understand is we have 75% less traffic hitting the server compared to this time last year and never had disk issues like this.

    iostat output:
    Code:
    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          1.50 1272.50 112.50 135.00 2236.00 11268.00  1118.00  5634.00    54.56    25.33  103.09   4.04 100.00
    dm-0         0.00   0.00 108.00 1408.50 2236.00 11268.00  1118.00  5634.00     8.90   265.76  175.37   0.66 100.00
    dm-1         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          1.01  28.14 70.85 111.56 1555.78 1109.55   777.89   554.77    14.61    13.83   75.96   4.96  90.45
    dm-0         0.00   0.00 72.36 138.69 1555.78 1109.55   777.89   554.77    12.63    15.50   73.56   4.28  90.40
    dm-1         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
    
    Stats from /proc/sys/vm/block_dump:
    Code:
    TASK                   PID      TOTAL       READ      WRITE      DIRTY DEVICES
    kjournald              593       1498          0       1498          0 dm-0
    pdflush              27441        425          0        425          0 dm-0, loop0
    lsphp5               18169        279         22        257          0 dm-0
    lsphp5               15794        240         54        186          0 dm-0
    kjournald             3092        123          0        123          0 loop0
    lsphp5               16402        118         25         93          0 dm-0
    lsphp5               18179        101        101          0          0 dm-0
    
    I've read that mounting the file system with noatime, nodiratime might help, but I do not know if this interferes with cpanel so I haven't risked it. Could this cause issues with cpanel?

    Is there any way of seeing what kjournald is writing? Anything I can do to troubleshoot this further?

    I'd really appreciate any help.
     
  2. mtindor

    mtindor Well-Known Member

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    Just a really wild guess.... did you upgrade from PHP 5.2 on a server with lots of PHP sites, especially ones that may have outdated PHP apps? If so, you're probably getting error_logs created in various folders underneath of public_html for many of your users. All of the 'deprecated' warnings are going to start being generated by default for any PHP app. If you have some hgh traffic sites with PHP scripts/apps that are out of date, it could be writing to many error_log files constantly.

    In EasyApache you can force it to not write the deprecation warnings. Although then people aren't going to be able to see why their outdated sites are breaking, or that their outdated sites need updating.

    At any rate, check and see if it's not a case of having a lot of error_log files created and being written to constantly. It's normal to see error_log files in various user directories where they have PHP scripts. So you'll actually have to look at which ones are updating frequently and how large they are getting.

    For instane, somebody running an old Joomla 1.0 site [especially with tons of addon components and such] are going to have a ton of error_log activity if the site is popular.

    M
     
  3. MarkPW

    MarkPW Member

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    I thought it might be PHP errors but having checked everything, although I found some errors relating to deprecated functions - namely a couple of directives enabled in php.ini that I have now turned off - I can find no problems. There are only 3 sites on the server and all work fine. They have no outdated PHP scripts and are throwing no errors on site nor in logs.

    Is there anything else I can try? Would cpanel function ok with the file system mounted with noatime, nodiratime?

    Thanks for your help.
     
  4. AlexCl

    AlexCl Active Member

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    Hi MarkPW,

    Are you using fcgi as the handler and / or Joomla for the website/s ?
     
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