help with dependencies

[Stanley Hopcroft]

Dear Sir,

I am writing to thank you for your letter and say

On Thu, Dec 19, 2002 at 08:34:19AM -0800, JKnash at bnyclearing.com wrote:
> I am having a little bit of trouble understanding how dependencies work.
> The documention isn't helping me all that much so I figured I'd ask for
> help.

that my experience is (not having inspected the dependency code - and I 
should: Mr Galstad annotates extensively his code) is that
'host' and 'service' in the templates refer to a service that depends 
upon the services running on another host, that given by the value of 
the 'dependent_host_name' and 'dependent_service_description'.


> I have a webserver named WWW1 that relies on a database server named
> DB1.  The database server is required for the webserver to be considered
> up.  Which would I put as the host_name and which would I put as the
> dependent_host_name?
> 

define servicedependency{
        host_name                       WWW1
        service_description             WWW1 web service
        dependent_host_name             DB1
        dependent_service_description   DB1 database service
        execution_failure_criteria      n       ; These are the criteria 
for which check execution will be supressed
        notification_failure_criteria   c       ; These are the criteria 
for which notifications will be supressed
        }

Check it out by forcing a passive service check with a HARD CRITICAL 
state on the DB1 service and see what state the WWW1 service is in.

> thanks,
> 
> Justin Knash
> Network Engineer
> BNY Clearing Services
> 
> 

Be aware that there are some gotchas with dependencies :-

1 the service may be checked before the 'dependent_service' is checked, 
so you could be be notified anyway

2 the default is to only suppress checks and notifications when the 
'dependent service' is in a HARD state.

You can work around the latter with the global config option 
soft_dependencies...  (see doc).

I don't know how to deal with the former (apart from changing the rates 
of service checks so that the 'dependent_service' [this is a perplexing 
name for me - I would have said the other one is dependent] is checked 
more frequently than the service that depends on this one).

HTH,

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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