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Nagios Alternative – Cost Calculator.

By David Mytton,
CEO & Founder of Server Density.

Published on the 12th November, 2014.

A common misconception in the industry is the notion that open source monitoring software is free. This is true if you’re looking at licensing alone, but there’s infinitely more factors to take into account than that. Being a great Nagios alternative, we decided to work out exactly how expensive Nagios is in comparison to our own server monitoring.

Server Density’s job as a competitor is to highlight some of the problems and difficulties of using Nagios, without damning the open source community and misleading anyone. Anticipating some critique of our calculations we’ve decided to write this article on our ‘workings’. It also gives you the ability to engage with us about the calculations – please comment below if you think we’ve gone wrong. If you can convince us, we’ll happily amend our math. For now though, here’s how we’ve worked it out.

Before you start

You’ll notice a common theme across many of these headings being the time Nagios takes to setup and use. In a world where time and money are completely unrelated, this is how the relationship between Server Density and Nagios looks:

  • Nagios saves you money.
  • Server Density saves you time.

Or

  • Nagios costs you time.
  • Server Density costs you money.

But of course this isn’t true, the age old idiom “time is money” couldn’t be more applicable to the world of fast moving tech startups, so:

  • Nagios costs you money.
  • Server Density costs you money.

Those principles form the basis of our Nagios cost calculator, to which we’ve created a monetary value for Nagios based on the time you’d expect to take setting up and maintaining the open source tool. You can evaluate the cost of a basic monitoring setup if you’d like, but if you need to replicate our monitoring infrastructure it’s best to keep all of the options ticked.

Nagios Cost Calculator

Nagios Hardware Requirements

A Nagios server isn’t cheap to run, they require a large amount of processing power, especially if you have a lot of servers:

Under 50 servers

To monitor anything under 50 servers we suggest something similar to the Amazon m3.medium instance type. At the time of writing (Nov, 2014) that’ll set you back $0.070 an hour, which totals to a yearly cost of $613.

Over 50 servers

Monitoring more than 50 servers will demand more from your Nagios server, so you’ll need to upgrade. For this we’d suggest an m3.xlarge instance. At the time of writing (Nov, 2014) that’ll set you back $0.280 an hour, which totals to a yearly cost of $2452.

We’ve used AWS as the cost benchmark as they’re constantly pushing costs down and are the most popular provider. We didn’t consider reserved instances because they add some complexity to calculating the cost due to the pre-purchase fees, which add to the overall setup cost of Nagios you don’t get with Server Density.

Need redundancy?

If you take monitoring seriously you’ll want to keep redundancy checked. To replicate how Server Density is deployed with full redundancy within our data centers combined with geographic redundancy of deploying into multiple facilities (your monitoring needs to be more reliable than what you’re actually monitoring!) you’ll need to have at least 2 servers each across 2 data centers. In the case that you’re monitoring under 50 servers that’s $613 * 4, if you’re monitoring over 50 it’s $2452 * 4.

This level of redundancy is necessary to ensure you can survive the failure of a node within one facility as well as the failure of the entire data center. Of course, this assumes you know how to set up Nagios in a redundant, load balanced cluster.

Once you get over 50 servers then it’s totally unacceptable to be running just a single Nagios server, so we forced this above 50 servers with our Nagios calculator.

How long does Nagios take to setup?

We’ve calculated the initial monitoring setup to take 2 working days. This can be shorter if you know what you’re doing or longer if you’ve never done it before. This is because it takes time to go through the installation process and in particular, get the initial config right.

How long does Nagios take to deploy across multiple server?

Once you’ve spent the 16 hours setting your Nagios server up, you still need to consider how long it takes to install the monitoring agent(s). There’s no shortage of config files when you’re running Nagios. It’s usually the initial setup that takes the longest, with each additional server only taking a few minutes to get up and running.

Nagios alerts configuration

Monitoring alerts need to be reliable and flexible. By default, Nagios limits alert delivery to email so it takes extra time to set up SMS alerts, or configure push notifications on your phone, plus the services you’ll want to use are often not free. SMS gateway reliability is important and with push notifications you need apps, or some 3rd party that supports generic notifications. Again, reliability has to be monitored. With Server Density, all of this is taken care for you at no extra cost. Even down to free SMS credits.

As part of the Nagios cost calculator, we estimate that setting up an alerting system that compares to the one we offer will take 8 hours of your time and have ignored the cost of using the external service such as for the SMS credits.

Nagios Graphing

It will take you a further 8 hours to install a plugin like nagiosgraph or configure an entirely separate system such as Cacti or Graphite – and even then, here’s the same data presented by Nagios and Server Density:

Nagios Alternative

Nagios Security

Keeping everything nice and secure is essential. It takes time to get some basic hardening on any server and we’ve budgeted a couple of hours for this. What we don’t include is ongoing security assessments and patches that we take care of for you with Server Density. This is particularly important if a piece of software is installed on every single one of your servers or is a key part of your systems…such as monitoring.

Monitoring your monitoring

With no redundancy set up then you’re going to struggle to monitor the performance of your Nagios server without 2 to monitor each other. In the instance of no redundancy, you’ll need to use a service like Server Density on our 1 server plan to make sure everything is okay with your single Nagios server.

Nagios Maintenance

By default our calculator is set to allow for 12 hours of maintenance every year. That’s one hour a month fiddling with preferences, tweaking configs, fixing problems, upgrading or even thinking about improvements to your monitoring setup.

Incident management

We assume you to spend 6 hours every year (30 minutes a month) on incidents relating to your Nagios monitoring servers. This could be a hardware failure, instance retirements, whole region/data center reboots, instance upgrades, dealing with backups or clearing out metrics data from disk space.

Worldwide locations for web checks

If you want availability monitoring, then your best bet is to pay for an external provider like Server Density or Pingdom. On which, a ’50 checks’ account will cost ~ $250/year (as of Nov 2014).

Setting up geographically dispersed monitoring locations and scheduling checks amongst them all is non-trivial, and is something you get as part of the product with Server Density.

Most of the time the calculator settings are defaults and can be changed based on how long you’d consider things to take you. We have tried to be fair to Nagios with our time estimations, because after all cost isn’t the only way we think we have an advantage over the open source competition. There are some cases when Nagios is cheaper (e.g. if you don’t value your time highly or with tiny numbers of servers…but then why are you setting up a complex monitoring tool like Nagios in the first place?!) but with all the functionality Server Density provides, we think we have a pretty good offer!

Thanks for taking the time to read through our justification, if you’d like to join the discussion please leave a comment below, or equally this reddit thread is home to some interesting comments – we love to reading and responding to your thoughts. Oh, and if you’re sick of Nagios, consider us next time you’re looking for a Nagios Alternative.

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