AWS Reserve Instance Billing

Question

I have about 8 EC2 Windows t2.small instances iam paying about $0.03 (on-demand) Total is about 5840 hrs/month. If I buy 1 reserve instance for 1 year is a total of about 8760 hrs

Will the bill for this reserve instance be applied to all my 8 EC2 pricing ? Or will it be only applied to 1 of them ?

I ask these because I am not sure I will have all 8 instances for 1 year, but I am sure I will have them for at least 3 months. So I can pay upfront for 17520 hrs of EC2 t2.small Windows.

All my EC2 run 24/7

Answer 1

As long as you run at least one t2.small instance running all the time, your reserved instance rate will be applied to that instance.

• If you have 8 instances running, 7 will be charged on-demand price one will be charged for reserved instance price.

• If you have 2 instances running, you will be charged one for on-demand and one for reserved instance.

• If you have no instance running, you will be charged for one reserved instance.

• If you will be running the instance for three months only, do not buy reserved instance since it is not cost effective. Instead try the Reserved Instance Marketplace , where some people sell their unused reserved instances.

Answer 2

If you buy 1 reserve instance for 1 year then you'll be charge separately for that 1 reserved instance.It is calculated on the basis of reserved instance rate.

Rest all will be charged on the "on-demand" basis rate.

Answer 3

The simplest way to think of a Reserved Instance is that you are pre-purchasing (annually or monthly) the right to run one matching instance every hour of the year at now hourly cost.

(Things get a bit more complicated with Linux per-second pricing.)