Nagios dependency question

[Scott Whitney]

Background:
a) Nagios runs "here"
b) There is a router "here"
c) It goes across the Internet to my coloc site (call it "there")
d) There is a router "there"
e) For the purposes of this example, there is 1 "machine" there
f) "machine" runs httpd
g) this httpd is shared for all web apps on the box, of which there are 55
h) I have a script which checks the status of this web app.

Here's my problem.  When the router, here, is down, I get 59 messages.  That
is, router "here", router "there", machine ping, machine httpd + 55 sites.

I can solve this using dependencies, but here's my question.

For the dependencies to work properly, each of the sites must be dependent
on:
    a) httpd
    b) ping machine
    c) ping router "there"
    d) ping router "here"

Let's assume I check this every minute.  My math says that this is roughly
280 hits on httpd per minute (55 * 5 + 5), 280 pings to the machine per
minute, 280 pings to the router there per minute and 280 pings to the router
here per minute.

This gets a little worse when you realize I actually have over 200 sites,
not 55.  Also on 7 boxes, not one, so we're looking at more like 1005 per
minute, spread unevenly across several boxes.

The question, then, is whether anyone has run into this and/or does Nagios
take this into consideration via any caching mechanism?  The documentation
says

"Before Nagios executes a service check or sends notifications out for a
service, it will check to see if the service has any dependencies. If it
doesn't have any dependencies, the check is executed or the notification is
sent out as it normally would be. If the service does have one or more
dependencies, Nagios will check each dependency entry as follows:
Nagios gets the current status* of the service that is being depended upon.
"

* by default this is the current HARD state

So...from where is it getting this information?  Further perusal through the
theory section helps me not at all...

Anyone have ideas on this?

Thanks,

Scott Whitney
swhitney at Journyx.com



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