FW: NDO Utils Question

[Wheeler, JF (Jonathan)]

> -----Original Message-----
> From: Christopher McAtackney [mailto:cristoir at gmail.com]
> Sent: 25 June 2009 14:51
> 
> Hi everyone,
> 
> I have a quick question about Nagios and NDOUtils I was hoping someone
> could answer.
> 
> What happens if the database that NDO Utils is using becomes
> unavailable? (e.g. the server has crashed).

The answer depends a lot on whether you are using Nagios v2 or Nagios
v3; we are using Nagios v2.11.  My understanding is that in Nagios v2,
the code that communicates with the event broker module in
single-threaded.  Therefore a problem with the SQL server can jam up
Nagios to the extent that it effectively stops running commands.  In
Nagios v3, threading has been rewritten and this problem no longer
exists.

> I'm assuming Nagios will continue to monitor and send notifications as
> normal, is this correct?

In Nagios v2 it seems that almost all activity is suspended when you are
using NDOutils and the MySQL server is unavailable; this continues until
the SQL server is restored.  One solution is to restart Nagios without
the broker_module.
 
> What about the service check results that would normally be passed to
> NDO Utils and then stored in the database? Are they queued somewhere?
> And if so, how is the capacity of this queue defined? If they are not
> queued, what happens? Will NDO Utils just throw an error for each
> result it tries to store in the database and fails? Will this affect
> the core Nagios process?

Results passing into the command pipe are stored.  The relevant
parameters are in nagios.cfg; they are external_command_buffer_slots and
check_result_buffer_slots - by default these are set to 4096 (see
documentation within the configuration file).

> Hopefully someone can provide some insight.

Hopefully this has

Jonathan Wheeler 
e-Science Centre 
Rutherford Appleton Laboratory
-- 
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