How can I tell which program is causing high iowait on Redhat?

Discussion in 'Linux Discussion' started by joe, May 16, 2008.

  1. joe Guest

    joe
    I have a Redhat enterprise 3 box that has to be rebooted sometimes several times a week because of crippling iowait (between 80% - 95%). This seems to occur randomly and suddenly, I'm running apache, mysql, mailserver. sometimes i go a month without problems, other times I'm rebooting every day, how do I track down the culprit program? top shows CPU usage is very low during iowait problem times.
    joe,
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  3. joe Guest

    joe
    Oh this is a tough one. My first guess is with the SQL or mail server. First, check the mail logs and see if you're getting mail bombed or something weird like that. Then check the DB transaction logs. Is there a lot of activity here? If neither of these turn up anything, try switching one of the services off for a day. See if you still get the problem. If you do, then turn that service back on and try another. If the problem goes away, then you've narrowed it down.
    joe,

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