Re: High load average mail server 5.3-RELEASE

From: Eric Anderson (anderson_at_centtech.com)
Date: 09/23/05

  • Next message: Joseph Koshy: "Re: Finding what's causing I/O" 
    Date: Thu, 22 Sep 2005 21:04:04 -0500
To: Francisco Reyes <lists@natserv.com>

    Francisco Reyes wrote:
    > On Tue, 13 Sep 2005, mariano benedettini wrote:
    >
    >> 91.3% idle
    >
    >
    > CPU is not the problem. :-)
    >
    >
    >> Mem: 1599M Active, 1704M Inact, 311M Wired, 189M Cache, 112M Buf, 14M
    >> Free
    >> Swap: 2023M Total, 184K Used, 2023M Free
    >
    >
    > Swap is not the problem.
    >
    >
    > Do
    > vmstat 10
    >
    > Watch the output.
    > In particular look at the first 3 columns.
    > procs
    > r b w
    > 1 1 0
    > 0 1 0
    > 1 1 0
    >
    > The left most column is CPU, the second column is disk IO.
    >
    > If you have a number in the "b" column and it never hits 0 you have an
    > I/O problem. You HDs are not catching up.
    >
    > If you are using NFS and the "b" colun is not high and hits 0 some/all
    > the time then the bottleneck is either the nfs connection or the nfs
    > server.
    >
    > For example I have some servers that the "b" column would be between 20
    > and 60 for a while. I am currently working on removing some of the load
    > of the machine. In my case more memory would help, but the computer
    > vendor we bought the machine from has sent us the wrong memory 3 TIMES!!

    Also, if it is an NFS server, one should check the cpu times on the nfsd
    processes. I've found that many times there aren't enough nfsd
    processes to take the load from many clients. Increasing the number
    (double it) often helps this. The max in 5.3 is 20, but you can easily
    change it and get around it.

    Eric 

    -- 
------------------------------------------------------------------------
Eric Anderson        Sr. Systems Administrator        Centaur Technology
Anything that works is better than anything that doesn't.
------------------------------------------------------------------------
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  • Next message: Joseph Koshy: "Re: Finding what's causing I/O"

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