So I visited grandma couple of days back and while talking about work and politics and all, she asked, so what’s this Nagios thing you guys are experts at?
I replied, its an “Enterprise Monitoring Solution” and she went like “Enterprise what now….”, and that actually got me thinking deep (something that i rarely do).
So anyway, to answer gramps pressing question, I gave this analogy.

Take for example a car

One thing cars these days come with are essential gauges to let us know what’s going on inside this technically complex electrical and mechanical marvel. This is called a dashboard.
So dashboards in a car gives us all these really cool information; and while cool, they’re also very essential for the well being and running of that car.

Most modern cars, you can tell the fuel levels, battery status, gear status, hand breaks statuses and what not. All essential right? And some more expensive cars like beamers, will even tell you that you’re due for a service soon!. Now, like many of us, the first thing I do when I power up my baby is to check this dashboard and see all that’s going on and when things are fine, engage gear, pull down that windscreen and breathe all the lovely smog from Kuala Lumpur air. {deep chesty cough x 2}
Now here’s where it gets difficult, lets take the challenge of watching over 10, or 100 or even 1000 cars all at the same time and to know at point in time and accuracy if one of these babies of yours isn’t behaving properly. While its possible to do one at a time but sometimes, it may be too late before you reach car no 99 to know that the battery has been completely discharged. Ouch!..can’t use that car until it gets fixed now… 🙁

Fear not car lover, here’s where Nagios comes to play. It is designed in such a way, doesn’t matter which type of car you drive and how the dashboard works, if it is in that dashboard, we can take all the important status information and put them in an easy to use web page for all those cars you manage.
Not only that, when a car reaches a fuel level of less than 10% (or anything you think its important to know about before it goes bonkers), Nagios can..
a) email you
b) send you smses
c) call you
d) put up a message on facebook for you
e) set an appointment with you mechanic
And there ya go, she got it, and thereafter, she went back straight to her room to sleep. But I knew she understood, I do….
Now back in geek-land…
Imagine those cars as servers, devices, applications/software, virtual or cloud infrastructure and what not. Each of these in some small or elaborate way have their own “dashboards” that come in a form of a simple log entry to a popups on your device saying something is wrong and what not. Again, to manage just this one, perhaps its very fine. But imagine managing hundreds, on top of that, a single server can potentially host tens of important apps, making it alone “a lot” to monitor.
The cool thing about Nagios is, you can really literally monitor whatever that server/apps/device  shows you, no gimmicks no joke..Monitor just about any type of hardware, OS, application and of a bare minimum, a plain ole log file!
Give it a try and see the power of Nagios for yourself.
Happy weekend.