Reserved Instances discounts are specifically for EC2 instances and don't apply to EBS volumes?

Question

Hi all

I'm going to set up Amazon OpenSearch. The price range is higher than expected, so I'm looking at the Reserved Instance. 
One question is, reserved EC2 Instances discounts are specifically for EC2 instances and don't apply to EBS volumes? If so, is there any other way to save EBS volume cost?

Thanks.

Steve_M · Accepted Answer

Reserved Instances only apply to the compute instances, and not the attached storage.

Cost optimisation steps for EBS include:

- always use **gp3** in preference to **gp2**, gives the same (or better) performance and is 20% cheaper
- only provision what you're going to use. If you provision 1TB but only use 100GB of it initially, you pay for the whole terabyte.
- nowadays there's almost never a use case for **io1**, unless you need a very large IOPS figure then a **gp3** topped up with extra IOPS and throughput will still be cheaper (for some workloads I've found **gp3** costs 10% of what the same spec of **io1** costs)
- the only reasons to go for **io2** is sub-millisecond latency, or extremely high IOPS figure. If your workload really does need these then you have to go with it, otherwise look at **gp3** topped up with extra IOPS and throughput

Also, if you have volumes that you know are going to be idle for an extended period (although I doubt that, because if you are purchasing RIs you're going to want to run them as close to all the time as you can) then snapshot them and delete them. You can restore from the snapshots later when you need to use the volume again.

The comparison table here may be of use https://docs.aws.amazon.com/ebs/latest/userguide/ebs-volume-types.html#vol-type-ssd

re:Post Agent · Answer

You are correct that Reserved Instance (RI) discounts are specifically for EC2 instances and do not apply to EBS volumes. RIs provide a discounted hourly rate for EC2 instances, offering significant savings compared to On-Demand pricing for steady-state workloads.

While RIs don't directly reduce EBS volume costs, there are a few strategies you can consider to optimize your EBS expenses:

1. Use EBS volume types appropriate for your workload: Choose the right EBS volume type based on your performance and cost requirements.

2. Leverage EBS Snapshots: Use snapshots to back up your data and only keep the necessary amount of EBS volume storage.

3. Delete unused EBS volumes: Regularly review and remove any unnecessary or orphaned EBS volumes.

4. Consider using instance store volumes: For temporary storage needs, use instance store volumes that come with certain EC2 instance types at no additional cost.

5. Monitor and optimize your EBS usage: Use AWS tools like CloudWatch to track your EBS utilization and identify opportunities for optimization.

6. Explore AWS Savings Plans: While not specific to EBS, Savings Plans can offer discounts on overall compute usage, which might indirectly help balance your total costs.

Remember, while these strategies can help manage EBS costs, the Reserved Instance discounts you're considering will only apply to the EC2 instance portion of your Amazon OpenSearch setup, not the associated EBS volumes.  
**Sources**  
[Amazon EC2 Reserved Instances - Amazon EC2 Reserved Instances and Other AWS Reservation Models](https://docs.aws.amazon.com/whitepapers/latest/cost-optimization-reservation-models/amazon-ec2-reserved-instances.html)  
[Reserved Instances - Amazon EC2 Reserved Instances - AWS](https://aws.amazon.com/ec2/pricing/reserved-instances/)

Reserved Instances discounts are specifically for EC2 instances and don't apply to EBS volumes?

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