Guesstimating Private Cloud TCO

I decided to try out the fantastic GessTimate. Guesstimate is a spreadsheet for things that aren't certain. I recently started to gather informations on private cloud TCO and I decided to see if i could quickly sketch out a probabilistic private cloud TCO model with it.

First, a little bit of literature review. On one side, we have the public cloud with an open pricing which make cost calculation and comparison straightforward. On the other we have the fog of war of the private cloud. There is very few non-behind paywall reports or information out there and here is the result of a (very) quick search for serious source about private cloud TCO data :

• Redhat Private Cloud TCO model which seems interesting but the lack of public methodology makes it difficult to assess. 
• EU report from e-InfraNet FP7 project : “Cloud Computing Economics: An evidence-based approach for Research Applications” . Their analysis show that private cloud operated by public agency operate at a fraction of the cost of AWS (25% of the cost in certain case) 
• Helix Nebula – The Science Cloud report : again in this case it show the the CERN openstack based cloud is a fraction of the cost of AWS (up to 25x). 
• The Magellan Report : DOE cloud were found to be 2–13x less expensive than typical commercial offerings. 

While all the numbers and comparison are highly interesting, I needed to find something usable for building a probabilistic TCO model. Finally, I found that many reports and online information referenced Amazon's James Hamilton analysis of the breakdown of cloud cost. His model boil down to the following :

• Servers: 57% 
• Networking equipment: 8% 
• Power distribution and cooling: 18% 
• Power: 13% 
• Other infrastructure: 4% 

For my own model I decided to use the following categories :

• Cost of money : The interest that could be earned if the amount invested it. Yep money is not free. 
• Software : Not everything is Open source, and even so you still need to deploy it. 
• Hardware : Server, SSD, HDD, etc… 
• Network :connectivity, switch, cable, router, etc... 
• People/Support : How much do you spend on maintaining your environment and deal with the customer need. 
• Aircon/power : Powering and cooling your cloud 
• Building Racking : Well it’s not like you are running everything in the cloud :) 

Now that we have a model, let's plug that into guesstimate. You can see in the picture below the result of the exercise. Note, DO NOT pay attention to the numbers, they are completely fantasist as I couldn’t get access to the latest IDC datacenter cost report.

Private Cloud TCO Guesstimate

What I ended up with is a really neat model where you can plug your own numbers and come up with a quick estimation of your private cloud TCO. It will take more work to generate a more accurate model but its good enough for basic estimation. In the mean time, you can find the source here. If you extend/change it, don’t forget to give me a shout. I am interested to see what other private cloud TCO model are out there.

Update 07/02/2016: +Carlo Daffara pointed me to his extremely detailed CAPEX / OPEX spreadsheet model. I'm going to see if I can translate it to guesstimate as a more advanced exercise.