Dependency issue

[Deborah Martin]

thanks for the tip but this doesn't work. 

It seems that its very dependent on when the next scheduled check will be.
If I set max_check_attempts to 5 for services
B or C, and then have max_check_attempts set to 1 on service A, it makes no
difference. Service B or C could still
be scheduled to be checked before service A. In fact, on the first check
attempt for service B, for example, a critical 
alert is generated. 

I want Nagios to detect that Service B or C is a dependency on Service A,
and then if Service A is alerting, suppress alerts for Service B or C. 
But nagios doesn't seem to do any kind of dependency lookup if a dependency
is already alerting. Kind of defeats, in my view, the logic
of dependencies. There is no point in Nagios telling me that Service B or C
is down, when Service A is down. Service A must be UP for any of its
dependencies to work. 

If however, Service A is OK, then yes - Service B or C should alert if
necessary. 

If I were to have 20 dependencies against a master service, I don't want 20
potential alerts being generated! Plus I want to know the EXACT cause of the
problem not have to hunt it down every time. Isn't that one of the points of
Nagios - to be able to finely tune plugin checks so that we can 
easily investigate a problem ? It seems that I needn't bother with
dependencies if this is how it's going to work. 

Does anyone else agree / disagree because it seems to me that either the
docs are not explaining dependencies correctly, or Nagios 
is not behaving correctly. I would appreciate feedback on this issue. 

regards,
deborah 




-----Original Message-----
From: Tedman Eng [mailto:teng at dataway.com]
Sent: 06 January 2006 20:35
To: 'Deborah Martin'; 'nagios-users at lists.sourceforge.net'
Subject: RE: [Nagios-users] Dependency issue


If Service B happens to be queued to be checked before Service A is, you'll
get notified of it's problem first, so that's why it's only sometimes that
you get this behavior.

As for simple solution to your question, increase the max_check_attempts of
Service B/C, so that Service A will error out before Service B/C does, thus
skirting the check queue phenomenon.


-----Original Message-----
From: Deborah Martin [mailto:Deborah.Martin at Kognitio.com]
Sent: Friday, January 06, 2006 3:11 AM
To: 'nagios-users at lists.sourceforge.net'
Subject: [Nagios-users] Dependency issue


Hi,     

I have setup dependencies which all seem to work fine to a point. 

Example : I have 1 host with 3 services 

                    HOST A 
                        | 
                    Service A (master service) 
                        |
            -------------------
            |                            | 
    Service B            Service C 

If service A  fails, checks and notifications are suppressed for Service B
and Service C which is fine. 

However, i've had a couple of situations where Service B or Service C may
fail first, generate an alert AND then Service A fails which also generates
an alert. 
Is there a way in Nagios that can flip over to only alerting for Service A
in this situation and supress anything for Service B and Service C until
recovery occurs. 

Do I need to define further service dependencies or use inheritance of
parent ? I've read the docs (several times) but can't seem to find the
answers there. 
                       
I'm using Nagios 2.0b4 / Suse 9.2. 

Any help, pointers to docs that can help, or even a padded cell would be
much appreciated! 

regards,
deborah 

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