Re: High load average mail server 5.3-RELEASE

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

  • Next message: Francisco Reyes: "Re: High load average mail server 5.3-RELEASE" 
    Date: Fri, 23 Sep 2005 15:25:50 -0500
To: Mariano Benedettini <marianobe@gmx.net>

    Mariano Benedettini wrote:
    > Thanks for all the replies. It's not a HD problem.
    > On monday I'll increase the number of nfsd processes and the number of
    > nfsiod on the client, setting both to 50,
    > I think that the nfs performance will be much better :-)

    50 nfsiod's may be a bit overkill, but you should experiment to find out.

    You should also increase the rsize and wsize parameters on the mount
    options for better efficiency.

    Eric

    > Eric Anderson wrote:
    >
    >> 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: Francisco Reyes: "Re: High load average mail server 5.3-RELEASE"