EC2 Saving plans

Question

I have c5.2xlarge instance ondemand that I use regluarly and will keep using. The price for that instance iz around 0.38$ per hour. If says that on EC2 saving plans 3 year commitment the instance price is ~0.145$. Does that mean if I buy saving plan for c5 family with commitment of 0.15$ per hour for 3 years, that instance of mine will be completely covered by that saving plan?

Accepted Answer

To answer your question in short - YES, if you buy that EC2 Savings Plan (SP) for C5 within the region where your instance is running with the hourly commitment 0.15$, then it will cover your running instance and you'll effectively be paying the discounted rate instead.

Though, as mentioned in the previous comments - it depends whether you are running 24/7 and whether you have any other C5 instances within the same region. If you don't run that instance 24/7 then during the hours when you are not running it, the discount from SP during those specific hours will be lost. But if it's only a few hours throughout the week, when your instance is not running, I'd say it's not a problem even if you lose a few hours - overall, you will be still getting a significant discount compared to paying on-demand. Moreover, if you have other C5 resources in the region running during those times - then the discount from SP will just automatically start applying to other matching instances.

Answer

It depends, if there are more C5 instances running, the Savings Plan will prioritize the instances with the highest saving amount, which may not include that specific instance. If the other instances have the same savings amount, it will then be applied at random to them and it may not be applied to the one you want.

Also, have in mind that SP is an hourly commitment, so every hour you don't have C5 instances running the Savings Plan is going to waste on those hours as commitments not used for the hour don't carry over the next hour.

It is good to first run the Savings Plans recommendations tool from your Billing and Cost Management console to see if there are any recommendations for that instance family, if there isn't it is probably because there were no  savings opportunities identified. If you see a recommendation to C5 family, you may click **View details**  to have more information if it is worth purchasing a Savings Plan and the amount to purchase so it is not underutilized.

Answer

How many hours a day does it need to be powered on for?
Not part of the answer but another train of thought.

EC2 Saving plans

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