I am trying to price up running an instance for 12 months. Part of that is trying to understand their reserved instances and if savings can be made by buying them.
Unfortunately Amazon's pages are cryptic at the best of times and damn right nonsense in some cases (or maybe I'm just a moron).
So I have the following questions:
- If I get a 12 months reserved instance, do I need to buy a "on-demand" instance first? Are you reserving the on-demand instance or is a "reserve" instance a type of instance within its self?
- What the heck is the "Offering Type" (or RIs) and why would a Heavy cost LESS than a Light instance? Shouldn't it be the other way around?
Just to give you an example. Let's say we want a "medium" Linux instance for 12 months. 100% monthly utilisation.
If we do a single on-demand instance that is $117.12/month. But if we do a single reserved instance that is ONLY $23.42/month.
That seems "too good to be true" in terms of discount/savings (80% off). So I am guessing that isn't how Reserved Instances work.
http://aws.amazon.com/ec2/pricing/
The first sentence under Reserved Instances is :
Reserved Instances give you the option to make a low, one-time payment for each instance you want to reserve and in turn receive a significant discount on the hourly charge for that instance.
In the table below you'll see that for each type of reserved instance there's an Upfront column followed by an Hourly column. To get your total annual cost for 100% utilization you would presumably add the 1 yr upfront cost to the hourly rate multiplied by the number of hours in a year (8760). You'll find that the total cost for a reserved instance is significantly less than that for an on-demand instance (where the upfront cost is zero but the hourly rate is higher).