Re: [logs] Problems/Questions on PEO

From: Sweth Chandramouli (loganalysisat_private)
Date: Tue Apr 02 2002 - 11:06:42 PST

  • Next message: Jon Stearley: "[logs] time-characteristic monitoring/analysis syntaxes"

    On Tue, Apr 02, 2002 at 10:37:03AM -0800, Devin Kowatch wrote:
    > Humm... the independent log hosts is an interesting idea.  Do you just
    > use the worm media as an archive?
    	Most places that use WORM do it for archival purposes; in
    theory, if you could find WORM media with a fast enough write speed, you
    could use it for initial queuing storage, but I don't know of anyone who
    has actually done so.
    
    > How difficult is it to go back and
    > reconsile the two logs?
    	It depends on how rigorous you want to be.  If the loghosts
    and the hosts logging to them are all on a quiet switched network with
    no intervening WAN links, you can probably get away with having each
    loghost pull over the most recently rolled logfiles from the other hosts
    and each doing a diff against the most recently rolled local logfiles.
    Once the networks start getting saturated or you start getting WAN-level
    latency, however, the machines will start receiving messages in different
    orders and with different timestamps.  The timestamp issue can be solved
    by just comparing the files after cutting the timestamps out, on the
    assumption that if all of the lines are present and in the same order
    then the timestamps are irrelevant.  Once the orders start differing,
    however, things get more interesting; you need to do things like
    comparing "rolling windows" of each file and trying to match a given
    line in the local file to any of the lines in the current window of the
    alternate file that has the same message text and a timestamp within
    some reasonable interval (a la diff, but with extra logic for the
    timestamps).
    
    	-- Sweth.
    
    -- 
    Sweth Chandramouli      Idiopathic Systems Consulting
    svcat_private      http://www.idiopathic.net/
    
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