Help understanding Amazon Web Services pricing

Question

Hi

I am trying to understand Amazon's pricing for regional data transfer... I have an EC2 instance in a us-east region and an S3 bucket in the EU. I am also using a 3rd party service that uses an EC2 instance that is only available in the US.

Can someone help to clarify what I am charged and where. Data can take one of 2 routes:

1. 1GB -> EC2a(US) -> EC2b(US) -> S3(EU)
2. 1GB -> EC2(US) -> S3(EU)

Amazon say:

Data transferred between two Amazon Web Services within the same region (i.e. between Amazon EC2 US and another AWS service in the US, or between Amazon EC2 Europe and another AWS service in Europe) is free of charge (i.e., $0.00 per GB). Data transferred between AWS services in different regions will be charged as Internet Data Transfer on both sides of the transfer.

I am using elastic IP address for both US EC2 instances and Amazon also charge for elastic IP data transfer at $0.01 per GB

Does this mean that for example 1 I pay as follows -

$0.1 (data in EC2a US) + $0.01 (elastic IP transfer) + $0.17 (data out EC2b US) + $0.1 (data in S3 EU)

EC2b which is our 3rd party service also have their own charges which I have left out here.

Thanks

Answer 1

By my understanding of it you're correct about the pricing, assuming that the two EC2 instances are in the same availability zone in the US and that you use the private IP address for transfer between these instances. If this is the case I believe the two scenarios you list will cost you the same.

Note that there are several availability zones within US-East (1a, 1b, 1c etc.), so not all instances are equal in this respect. If your third party service doesn't let you choose the availability zone for your EC2 instance you'll need to specify the zone to match when you start up your EC2 node.