heads-up: trap avalanche depletes swap and leads to killing Nag, Apache, named, ...
Stanley Hopcroft
Stanley.Hopcroft at IPAustralia.Gov.AU
Fri May 16 11:43:43 CEST 2003
Dear Sir,
I am writing to thank you very much for your letter and say,
On Thu, May 15, 2003 at 09:33:57AM +0200, Tom DE BLENDE wrote:
>
> Was flap detection enabled for that passive service? Shouldn't flap
> detection prevent that notification flood?
I am very grateful for your helpful suggestion.
I have enabled the global config directive in nagios.cfg and await with
much interest the next occurrence.
<offtopic>
I have been writing some very unsafe and inefficient CGIs recently that
today subjected the Nag host to a 1-1.5X memory over-commit (3-400 MB
when RAM + swap == 512 MB).
Apart from the OS killing the apache child running the CGI, all was
well. It appears that the most dangerous thing is a large number of
processes rather than a few big ones
</offtopic>
Thanks for the heads up about this.
Nag is simply __stuffed__ with sophisticated innovations such as this
(and freshness checking).
Given that the docco suggests (in at least two places) that
'Before I go any futher, let me say that flapping detection has been a
little difficult to implement. How exactly does one determine what "too
frequently" means in regards to state changes for a particular host or
service?
When I first started looking into flap detection I tried to find some
information on how flapping could/should be detected. After I couldn't
find any, I decided to settle with what seemed to be a reasonable
solution. The methods by which Nagios detects service and host state
flapping are described below...'
this is a new innovation, how well does it work ?
>
> Kind regards,
> Tom
>
Yours sincerely.
--
------------------------------------------------------------------------
Stanley Hopcroft
------------------------------------------------------------------------
'...No man is an island, entire of itself; every man is a piece of the
continent, a part of the main. If a clod be washed away by the sea,
Europe is the less, as well as if a promontory were, as well as if a
manor of thy friend's or of thine own were. Any man's death diminishes
me, because I am involved in mankind; and therefore never send to know
for whom the bell tolls; it tolls for thee...'
from Meditation 17, J Donne.
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