Host Dependency Logic

Anastasios Zafeiropoulos mls at freemail.gr
Wed Mar 24 04:05:58 CET 2004


Hello world,

I'm having trouble with a Host dependency misconfiguration or why not, with a bug in Nagios' Dependency logic process and 

notification.

I am using version nagios-1.2-0.rhfc1.dag which was a prebuilt package from Dag Apt repository site.
===================================================
My Topology:
===================================================

Nagios machine --- RT1 -- RT2 -- RT3 


====================================================
The problem
====================================================

When RT1 goes down, or the RT1-RT2 Link goes down, Nagios will notice that at random, while he is checkong a service or 

HOST_ALIVE function to any part of the network that is down. Let's assume that the first Host that Nagios found dead was RT3. 

Nagios didn't get any reply from RT3, so RT3 will be kept in SOFT down state. 

Next the RETRY proccess will take place. The max_check_attempts are 30 for each host. That's because the links are not 

reliable at all so we want to be a little elastic with the Notifications.

At the time that we reach the Retry #30, Nagios assumes that RT3 IS DOWN, puts it in HARD DOWN state and looks to find any 

dependencies associated with the RT3. If you look below, RT3 is dependent upon RT2. So it will continue with try pinging RT2.

While Nagios is trying to determine whether the RT2 is alive or not, suddendly, the RT1-RT2 link comes up and all the network 

is now reachable by Nagios. I notice here that the max_checks_attempts havent timed out. So Nagios will take a response from 

RT2 and it will put it in A HARD OK State.

The result will be NOT to check RT3 again to see if he is up as RT2. So, a notification will be sent reporting that RT3 is 

down. This is FAKE. The whole network was down!

Below I provide you my configuration. Maybe sth goes wrong with my conf files.

Thanks in advance guys

====================================================
My dependecies.cfg file
====================================================

define hostdependency{
 host_name   RT2
 dependent_host_name  RT3
 notification_failure_criteria d,u
 }

define hostdependency{
 host_name   RT1
 dependent_host_name  RT2
 notification_failure_criteria d,u
 }


===================================================
My hosts.cfg
===================================================

define host{
 use   generic-host
 host_name  RT1
 alias   Wireless 1
 address   213.5.0.34
 check_command  check-host-alive
 max_check_attempts  30
 notification_interval 0
 notification_period 24x7
 notification_options d,u
 }


define host{
 use   generic-host
 host_name  RT2
 alias   tsapi.twmn
 address   10.107.13.1
 parents   RT1
 check_command  check-host-alive
 max_check_attempts  30
 notification_interval 0
 notification_period 24x7
 notification_options d,u
 }


define host{
 use   generic-host
 host_name  RT3
 alias   Wireless Internet
 address   212.34.23.4
 parents   RT2
 check_command  check-host-alive
 max_check_attempts  30
 notification_interval 0
 notification_period 24x7
 notification_options d,u
 }



____________________________________________________________________
http://www.freemail.gr - δωρεάν υπηρεσία ηλεκτρονικού ταχυδρομείου.
http://www.freemail.gr - free email service for the Greek-speaking.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://www.monitoring-lists.org/archive/users/attachments/20040324/03e4bb90/attachment.html>


More information about the Users mailing list