AWS Revenue and Estimated Running Costs

Here is my very rough estimate on how many servers AWS have and their infrastructure costs:

https://docs.google.com/spreadsheets/d/1lIL-ChZxuZOHFE-7qVMUWAPt3mJ0A4W_4x8t0NxXQfg/edit?usp=sharing
Model based on the following assumptions:
- AWS revenue (latest quarterly revenue x 4): http://phx.corporate-ir.net/phoenix.zhtml?c=97664&p=irol-presentations
- 20,000 employees : http://blog.zorangagic.com/2016/12/how-many-employees-does-aws-have.html
- Salary: https://www.glassdoor.com/Salary/Amazon-com-Salaries-E6036.htm
- Server overprovisioning: http://blog.zorangagic.com/2016/12/ec2-instances-peak-cpu-utilisation.html
- According to AWS guru James Hamiliton (VP and Distiguished Engineer) servers are the single biggest cloud cost:
http://blog.zorangagic.com/2014/05/the-cost-of-cloud.html

http://perspectives.mvdirona.com/2010/09/overall-data-center-costs/

This above model still has total servers at less than 1 million, yet most analysts estimate that AWS have over a million servers. James Hamilton during his re:Invest keynote suggested that several AZs have over 300K server and data centres are built to accommodate up to 80K servers. If a single, big AZ has 300K servers then it implies that 15 regions each with 2+ AZs would definitely have over a million servers.


So I am puzzled as to why AWS need such large number of servers when server utilization rates average between 10% and 20% across the industry and it would be easy to over provisioning servers as demonstrated in my model?

Found a very old tweet from Werner Vogels suggesting no oversubscription:

Yet, today all modern cloud platform use some form of over subscription:
https://aws.amazon.com/blogs/aws/cloud-computing-server-utilization-the-environment/
http://perspectives.mvdirona.com/2015/05/greenpeace-renewable-energy-and-data-centers/
https://www.sciencelogic.com/blog/netflix-steals-time-in-the-cloud-and-from-users
https://forums.aws.amazon.com/thread.jspa?messageID=242262&#242262

Maybe AWS has such large number of servers as internal Amazon infrastructure could now also be running in AWS data centres including Amazon Video/Music/Audible/Go/Echo/Amazon Cloud Drive/etc, etc?

If anyone has a clue drop me a note: zorang at gmail.com.