Question regarding Dependencies

[Dale Hobbs]

Great, Thanks for your help

 

-----Original Message-----
From: Darren.Lichty at alltel.com [mailto:Darren.Lichty at alltel.com] 
Sent: Friday, August 20, 2004 8:39 AM
To: Dale Hobbs; nagios-users at lists.sourceforge.net
Subject: RE: [Nagios-users] Question regarding Dependencies

 

No, Nagios should take care of this for you.

If it determines the host is down, it should notify you on the host, and
not all the individual services.

 

-Darren

	-----Original Message-----
	From: Dale Hobbs [mailto:dhobbs at chancery.com]
	Sent: Friday, August 20, 2004 10:34 AM
	To: Lichty, Darren; nagios-users at lists.sourceforge.net
	Subject: RE: [Nagios-users] Question regarding Dependencies

	Thanks Darren that clears things up immensely. 

	 

	One more question for you then. Say I have one server that has 6
services being checked. If that server goes down then I don't want to be
notified that the other 6 services are down as well. Would I use service
dependencies for this?

	 

	-----Original Message-----
	From: Darren.Lichty at alltel.com [mailto:Darren.Lichty at alltel.com]

	Sent: Thursday, August 19, 2004 7:51 PM
	To: Dale Hobbs; nagios-users at lists.sourceforge.net
	Subject: RE: [Nagios-users] Question regarding Dependencies

	 

	Dale:

	I believe what you are looking for is a parent-child
relationship, rather than a host-dependency.

	 

	Given the following network (forgive the ASCII art ;-) ):

	            Nagios
	                |
	           Firewall
	                |
	        *-------*-------*
	        |       |       |
	        A     B     C

	I would set this up as:

	        define host{
	                host_name       A
	                parent          Firewall
	        }

	 

	        define host{
	                host_name       B
	                parent          Firewall
	        }

	 

	        define host{
	                host_name       C
	                parent          Firewall
	        }

	
	        define host{
	                host_name       Firewall
	        }

	You will note that there is no parent defined for 'Firewall'.
This is because 'Firewall' is local to Nagios (meaning, no the same
network/subnet).

	 

	In this case, if any of 'A','B', or 'C' goes down, Nagios will
check 'Firewall'.  If 'Firewall' is down, Nagios will tell you about it,
but NOT about 'A', 'B', or 'C' ('Firewall's children).  This will show
up in the web interface as a 'network outage', instead of a simple
'host' outage.

	 

	I do not use host dependencies personally, so I could not
comment as to a scenario in which they would be useful.

	 

	Important note however, if you want 'Firewall' to be checked
ONLY when any of it's children are down, do not define any services for
this host.  If, however, you want Nagios to "active" check this device,
setup a simple 'check_ping' service for it.  I have not completely
tested this out, but I do believe that having an "active" check on
firewall in this configuration will allow Nagios to pick up a failure on
that device quicker (this may not be the case thought).

	 

	I hope that helps.

	 

	-Darren

	 

	-----Original Message-----
	From: nagios-users-admin at lists.sourceforge.net
[mailto:nagios-users-admin at lists.sourceforge.net]On Behalf Of Dale Hobbs
	Sent: Thursday, August 19, 2004 11:14 AM
	To: nagios-users at lists.sourceforge.net
	Subject: [Nagios-users] Question regarding Dependencies

		For give me if this question has been asked before. I
have read the docs in regards to dependencies but am still a bit unclear
as to the internal workings.

		 

		If I have 3 servers (www1, www2, www3) on the outside of
my firewall with the following dependencies set up for each of the 3
servers:

		 

		define hostdependency{

		        host_name                       www1

		        dependent_host_name        firewall

		        notification_failure_criteria   d,u

		        }

		 

		If my firewall goes down, obviously it will notify me
that the firewall is down but will it also notify me that it can't
contact each of the 3 servers as well? Also if one of the servers goes
down is Nagios smart enough to check the firewall first to make sure
that it is still available before notifying me that the server is down
in case that it can't contact the server because the firewall is down?

		 

		 

		 

		Dale Hobbs 
		End User Support 
		Chancery Software -- The Right Partner. The Right
Solution. 
		Tel: 604-294-1233 Ext.4744 
		Fax: 604-294-2225 
		Email: dhobbs at chancery.com 
		http://www.chancery.com <http://www.chancery.com/>  

		 

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