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Exim spiking the load on my server

Discussion in 'General Discussion' started by evisions, Nov 15, 2004.

  1. evisions

    evisions Well-Known Member

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    I'm having an issue which seems to be from exim and cppop on my server. I'm currently running version 9.9.8-S6. The load on my server is generally under 5 for normal operation, but recently I have seen gigantic spikes (I saw as high as 150!). Once I'm able to restart exim the load drops back to normal. Cppop also seems to cause issues, I saw a load of 25, and once I restarted cppop the load dropped back down. I'm not able to find any issues in my log files that point to these issues. Naturally my clients are very upset.

    Can anyone help me locate the source of this issue? The problem seems to be cropping up regularly, if I don't fix it very soon I will start loosing clients....
     
  2. chirpy

    chirpy Well-Known Member

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    Need more information :)

    Have you altered exim.conf in any way? Any changes directory or through the WHM > Exim Configuration Editor?

    Have you installed the clamavconnector?

    How much physical RAM do you have in your server and what does free show?

    Have you tried inspecting the exim logs to find out what's happening:

    tail -f /var/log/exim_mainlog

    Have you got an iptables firewall installed and have you checked its logs?

    Have you enabled cppop POP3 connection flooding in WHM > Tweak Settings

    Lastly, are any of your disk partitiions nearly full?
     
  3. evisions

    evisions Well-Known Member

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    Thanks for the response Chirpy,

    > Have you altered exim.conf in any way? Any changes directory or through the WHM > Exim Configuration Editor?

    Yes, I added a dictionary attack blocker based on instructions on this page:
    http://www.webumake.com/free/eximdeny.htm

    I believe that is the only edit currently in my exim.conf, I made the changes through WHM. I had made some other changes to my exim.conf but I recently had to restore my system from backup and I believe those changes were lost. I can post the exim.conf if you want.

    > Have you installed the clamavconnector?

    no, I'm not sure what that is

    > How much physical RAM do you have in your server and what does free show?

    512 MB

    Currently Top shows:
    Mem: 513788k av, 502940k used, 10848k free
    Swap: 4192956k av, 260772k used, 3932184k free

    > Have you tried inspecting the exim logs to find out what's happening:
    > tail -f /var/log/exim_mainlog

    I have looked at it, but have not been able to determine what the issue is.

    > Have you got an iptables firewall installed and have you checked its logs?

    Yes I do, but I haven't checked it's log. I'm not sure where it is logged at unless it is just in /var/log/messages.

    > Have you enabled cppop POP3 connection flooding in WHM > Tweak Settings

    Yes.

    > Lastly, are any of your disk partitiions nearly full?

    /dev/hdc6 70516892 43301064 23633740 65% /
     
  4. chirpy

    chirpy Well-Known Member

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    Well, the exim dictionary attack should help performance, rather than raise it. If you could post your exim.conf as an attachment .txt file attachment I'd be happy to look at it.

    From your memory information (though you didn't post the cache level) it looks like you may be memory thrashing. You're using 33% of memory in use is being swapped out to disk which could be a significant problem and would explain the high server load as the server is having to spend a lot of CPU cycles and disk I/O swapping those pages in and out.

    It might depend on what else is running on the server (if there are some things running that needn't be, shutting them down might free up sufficient memory) that you simply need more RAM for your servers needs.
     
  5. evisions

    evisions Well-Known Member

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    Hi Johnathon,
    Thanks for the answer, if it is just memory that is an easy fix. It seems to be inconsistant so I was worried it is something more serious. I've attached my exim.conf, if you could take a look at it that would be great.

    I've also had a couple of users complain that they are getting some mail delayed by several hours (inconsistantly, most mail comes right through). Could this also be caused by low memory?

    Thanks,
    Chad
     

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  6. chirpy

    chirpy Well-Known Member

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    That's usually down to servers loads being > 3 for periods of time. At that point Exim, by default, suspends queue processing. If you have the Exim queue run in WHM > Tweak Settings set to 60 (the default) then it can take an hour after an email is queued for it to be processed. Of course, if when the queue run time comes again the server is heavily loaded, then the queue won't process and the email is delayed again.

    So, yes low memory causing high server load average can cause email delivery to be delayed sporadically.

    I'll check your exim.conf...
     
  7. chirpy

    chirpy Well-Known Member

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    Your exim.conf looks fine. You might want to update it to the very latest version to add the split spools directive which does help on very busy mail servers:

    /scripts/exim4 --latest
     
  8. rvskin

    rvskin Well-Known Member
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    Does any error apear in /var/log/exim_paniclog?
     
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