Plugins which monitor several things

[Trond Hasle Amundsen]

Hi Nagios developers,

Let me first say thanks for a first-rate product! Ok, I'll get to the
point :)

Nagios deals poorly with plugins that monitor more than one thing. I'll
try to illustrate with an example. Consider a plugin that monitors the
fill grade of all mounted filesystems. The filesystems will be different
for all monitored hosts, but for convenience the plugin is the same
across all hosts (same service etc.).

The pedantic Nagios way, as I understand it, would be to add exactly one
service for each filesystem on each server. This is unmanageable if you
have more than a few hosts, so you'll stick with the plugin that
monitors all mounted filesystems.

The problem then becomes that you can't do operations lik adding
downtime, acknowledge etc. on the one filesystem that is full. These
operations pertain to the service, which includes all filesystems on the
host. If another filesystem becomes !OK, you won't know if you've added
downtime on the service, for example.

My question is, do you consider this to be a problem? Would it be
feasible to add functionality into Nagios to handle this?

I've not looked at the code, so I can't say for sure, but adding
fine-masked control for "sub-services" would probably include adding a
second protocol for plugin output. The plugin would have to somehow
identify (e.g. by number) each of the "sub-services" which are
monitored. I'm a bit conflicted about this, since the simplicity of the
plugin output is one of Nagios' strenghts IMHO.

What are your thoughts on this?

PS. The filesystem example is just for simplicity. This problem applies
to any plugin that monitor several things, such as hardware monitoring
plugins.

Cheers,
-- 
Trond H. Amundsen <t.h.amundsen at usit.uio.no>
Center for Information Technology Services, University of Oslo

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