On Fri, 2010-03-12 at 13:28 -0500, mcclainje wrote: 
> Anyone using this?  Any helpful advice?  We are seeing quite a bit of 
> variation in the numbers and are not sure if we should be concerned.


We have created that probe primarily as a convenient means of tracking
InterMapper performance on customer machines in the event of a
performance problem; you are, of course, welcome to use it for your own
purposes, but you should be aware that it remains in the Experimental
section for a reason (we only promise that it will change, and in ways
that probably aren't backwards compatible).  The numbers that are in
there at present are mostly there because we're working on things
related to them.  The engine frequency is the canary in the coal mine;
if it remains near 66 Hz, everything else is probably fine with the
server.  If that number drops substantially (below 30Hz), you may see
evidence of impaired performance; the other numbers might help us to
pinpoint the cause.

There are two pieces of advice that might be helpful when using it; one
piece of advice is not to put a notifier on it; in our testing, most
operating systems have some kind of maintenance routines that they go
through every night which adversely affects InterMapper's performance
even under otherwise optimal conditions (if you're using the database,
the nightly database maintenance is one such task).  As a result, you'll
almost certainly get a notification in the wee hours of the morning
every day.

The other piece of advice is that you should only have a single instance
of a device using that probe against a particular server.  The numbers
reported are all "since the last poll" numbers, and if you have two
devices polling the same InterMapper server, they will share data and
the numbers that you see will be difficult to interpret properly.  The
numbers will also change in meaning if you change the poll interval
because of this.  

As an example, one way you might see quite a bit of variation is if you
have enabled the database server, which pulls data from InterMapper once
a minute, but the engine status probe is set to poll once every 30
seconds; during the 30 seconds around the top of a minute, you would see
a lot more activity while InterMapper responds to that request for data
than you will during the 30 seconds around the bottom of a minute.

-- 
Stephen Ryan
Dartware, LLC

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