CODEWITHSUNDEEP
amazon-web-servicesdockeramazon-ecs
H van Maanen
H van Maanen

Reputation: 31

Configure ECS to use Reserved Instances

ECS (EC2 Container Service) works with Auto Scaling Groups. But is it possible to use ECS with Reserved Instances? I ask this because Reserved Instances are cheaper.

Upvotes: 3

Views: 4153

Answers (1)

mcheshier
mcheshier

Reputation: 745

When you reserve an instance, you get billed for all possible hours of use for the reservation period at the beginning of the period, whether you use the hours or not. At the end of the billing period, AWS will reconcile your usage hours vs. reserved hours.

This means that regardless of whether you stopped or started the instance automatically, you're still paying for it, albeit at the lower reserved price. Reserved instances do make sense for the 'non-elastic' portion of your ASG, like instance 1 of 3 that always needs to be up. If you have a lot of the same instance type, you can also 'float' reserved instance hours by estimating capacity and making your best guess as to how many auto-scaled hours you will end up needing.

This approach is good if you have an established track record of use, like peak load between 7AM and 5PM PST. You can do the math from there.

My preference for elasticity in ECS is to use the spot market. You will pay much much much less for them and autoscaling works great.

Upvotes: 2

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