Main Points are,

Reserved instances are one of the types of purchase options available for EC2 instance to enable you to optimize your costs based on your needs.

Tenancy defines how EC2 instances are distributed across physical hardware and obviously it affects pricing. The main thing here, with a tenancy selected(say dedicated), you can also decide your purchase options(either spot or on-demand or reserved)

So answering your question based on the above statements,

  1. Can that affect the performance of my application deployed on that instance? What happens when the application has more load/requests? No it doesn't, It is totally based on the instance type that you've selected. When application has more load, try to add more instance or change the type of instance.

  2. Are Reserved Instances also working with shared tenancy? Yes, explained above.

  3. Reserved Instancies service is creates instances or it's possible to buy, ie 10 RI T2 type to apply to my current instances? It's just a pricing option.

you can read these two docs for getting a better understanding.

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-purchasing-options.html

https://aws.amazon.com/ec2/pricing/dedicated-instances/

Answer from Sam on Stack Overflow
🌐
AWS
aws.amazon.com › amazon ec2 › pricing › reserved instances
Reserved Instances - Amazon EC2 Reserved Instances - AWS
3 days ago - Then this RI’s discounted rate can automatically apply to two m4.xlarge instances in us-east-1a or four m4.large instances in us-east-1b. ... Offering class: There are two classes of RIs: Convertible and Standard. Convertible RIs can be exchanged for different Convertible RIs of equal or greater value. Term: AWS offers Standard RIs for 1-year or 3-year terms. Reserved Instance Marketplace sellers also offer RIs often with shorter terms.
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Amazon Web Services
docs.aws.amazon.com › amazon ec2 › user guide › amazon ec2 instances › amazon ec2 billing and purchasing options › reserved instances for amazon ec2 overview
Reserved Instances for Amazon EC2 overview - Amazon Elastic Compute Cloud
Reserved Instances provide you with significant savings on your Amazon EC2 costs compared to On-Demand Instance pricing. Reserved Instances are not physical instances, but rather a billing discount applied to the use of On-Demand Instances in your account.
Discussions

I thought I understood Reserved Instances but clearly not - halp!
Reservations, like savings plans, are a billing abstraction. In this case, you are committing to pay for a specific instance size, in a specific instance family, in an AZ or Region, in exchange for a discount. You do not have any assurance that you will actually be able to spin up that kind of instance however. Reservations also have some amount of flexibility, but upwards. For example, if you purchase 2 m3.large reservations, they will primarily apply to 2 running m3.large instances. If none are running, it will try to apply against a running m3.xlarge instance. Reservations are more limiting than savings plans and I would personally preference savings plans for their flexibility. More on reddit.com
🌐 r/aws
15
1
October 7, 2024
amazon web services - How does AWS know to apply reserved instances price to the EC2 running 24/7 and not part time? - Stack Overflow
Our organization has many EC2 on-demand instances. We never looked at the reserved instance pricing because we thought we had to pay up-front. But I see that now there are reserved instance with no... More on stackoverflow.com
🌐 stackoverflow.com
Is it not possible to buy t4g reserved instances for RDS?
I've got 3 more months on my t2.medium reservation and would love to switch to t4g for the next 3 years. Any chance this will happen soon u/jeffbarr ? More on reddit.com
🌐 r/aws
9
5
June 22, 2021
AWS OpenSearch Service - Buy/Sell Reserved Instances
Your best bet would be to reach out to AWS, they don’t seem to have opensearch listed under sellable or exchangeable RIs. More on reddit.com
🌐 r/aws
3
1
September 19, 2021
Top answer
1 of 2
1

Main Points are,

Reserved instances are one of the types of purchase options available for EC2 instance to enable you to optimize your costs based on your needs.

Tenancy defines how EC2 instances are distributed across physical hardware and obviously it affects pricing. The main thing here, with a tenancy selected(say dedicated), you can also decide your purchase options(either spot or on-demand or reserved)

So answering your question based on the above statements,

  1. Can that affect the performance of my application deployed on that instance? What happens when the application has more load/requests? No it doesn't, It is totally based on the instance type that you've selected. When application has more load, try to add more instance or change the type of instance.

  2. Are Reserved Instances also working with shared tenancy? Yes, explained above.

  3. Reserved Instancies service is creates instances or it's possible to buy, ie 10 RI T2 type to apply to my current instances? It's just a pricing option.

you can read these two docs for getting a better understanding.

https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-purchasing-options.html

https://aws.amazon.com/ec2/pricing/dedicated-instances/

2 of 2
1

Can that affect the performance of my application deployed on that instance? What happens when the application has more load/requests?

No it can't. There is no effect.

Are Reserved Instances also working with shared tenancy?

It does not apply to you. RI is only pricing discount, not related to the fact whether you use shared tenancy, dedicated instances.

Reserved Instancies service is creates instances or it's possible to buy, ie 10 RI T2 type to apply to my current instances?

It does not create new instances. Its just a pricing discount.

🌐
Amazon Web Services
aws.amazon.com › cloud financial management › cost optimization with aws › reserved instances
Reserved Instances
4 days ago - You can make rightsizing a smooth ... ... Amazon EC2 Reserved Instances (RI) provide a significant discount (up to 75%) compared to On-Demand pricing and provide a capacity reservation when used in a specific Availability Zone....
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Rackspace
docs.rackspace.com › docs › reserved-instances
Reserved Instances
Reserved Instances play an important role in helping you manage the overall costs of your AWS environments. In cases where you plan to have sustained 24x7 usage of one or more EC2 or RDS instances of the same instance type in the same availability ...
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Clozon
clozon.com › home › clozon blog template › aws reserved instances vs savings plans – compared with examples
AWS Reserved Instances vs Savings Plans - Compared with examples - Certified experts to guide your DevOps and AI/ML initiatives towards successful outcomes.
January 21, 2025 - Reserved Instances and Savings plans are commercial offerings and do not impact the EC2 Servers you run. AWS calculates your actual EC2 instance usage hours, applies discount on the charges as per Reserved Instances or Savings Plans purchased ...
Find elsewhere
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Virtana
virtana.com › home › aws reserved instances, the definitive guide (2019)
AWS Reserved Instances, The Definitive Guide (2019) – Virtana
May 12, 2023 - AWS uses these attributes to match your RI purchase to instance usage: Instance Type: A specific ratio of CPU/memory/storage/networking capacity optimized for a particular workload type · Platform: Linux/UNIX, SUSE Linux, Red Hat Enterprise Linux, Microsoft Windows Server, and Microsoft SQL Server · Scope: Whether the Reserved Instance applies to a Region or specific Availability Zone.
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Reddit
reddit.com › r/aws › i thought i understood reserved instances but clearly not - halp!
r/aws on Reddit: I thought I understood Reserved Instances but clearly not - halp!
October 7, 2024 -

Hi all, bit of an AWS noob. I have my Foundational Cloud Practitioner exam coming up on Friday and while I'm consistently passing mocks I'm trying to cover all my bases.

While I feel pretty clear on savings plans (committing to a minimum $/hr spend over the life of the contract, regardless of whether resources are used or not), I'm struggling with what exactly reserved instances are.

Initially, I thought they were capacity reservations (I reserve this much compute power over the course of the contracts life and barring an outage it's always available to me, but I also pay for it regardless of whether I use it. In exchange for the predictability I get a discount).

But, it seems like that's not it, as that's only available if you specify an AZ, which you don't have to. So say I don't specify an AZ - what exactly am I reserving, and how "reserved" is it really?

🌐
Amazon Web Services
docs.aws.amazon.com › amazon ec2 › user guide › amazon ec2 instances › amazon ec2 billing and purchasing options › reserved instances for amazon ec2 overview › how billing works with reserved instances
How billing works with Reserved Instances - Amazon Elastic Compute Cloud
For information, see AWS Free Tier ... Reserved Instances are billed for every clock-hour during the term that you select, regardless of whether an instance is running. Each clock-hour starts on the hour (zero minutes and zero seconds past the hour) of a standard 24-hour clock.
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AWS
calculator.aws
AWS Pricing Calculator
AWS Pricing Calculator lets you explore AWS services, and create an estimate for the cost of your use cases on AWS.
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Vantage
handbook.vantage.sh › aws › concepts › reserved-instances
Reserved Instances - Cloud Cost Handbook
Reserved Instances (RIs) are one of the most popular and high-impact cost-reduction methods you can leverage for cutting your bill. Reserved Instances give you the ability to pay upfront for certain AWS services to receive a discount.
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CloudZero
cloudzero.com › home › blog › a roadmap to aws savings plans vs. reserved instances
A Roadmap To AWS Savings Plans Vs. Reserved Instances
June 10, 2025 - AWS Reserved Instances (RIs) is a discount pricing model that enables organizations to save up to 75% on On-Demand Instances when they purchase them in advance for a fixed term of one or three years.
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Amazon Web Services
docs.aws.amazon.com › amazon ec2 › user guide › amazon ec2 instances › amazon ec2 billing and purchasing options › reserved instances for amazon ec2 overview › use your reserved instances
Use your Reserved Instances - Amazon Elastic Compute Cloud
If you purchased a regional Reserved Instance, you must specify an instance type from the same instance family as the instance type of your Reserved Instance. For example, if you specified t3.xlarge for your Reserved Instance, you must launch your instance from the T3 family, but you can specify any size, for example, t3.medium.
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TechTarget
techtarget.com › searchaws › definition › AWS-Reserved-Instances-Amazon-Reserved-Instances
What are AWS Reserved Instances? | Definition from TechTarget
AWS Reserved Instances (RIs) refer to compute capacity that can be reserved on Amazon Elastic Compute Cloud (Amazon EC2) and Amazon Relational Database Service (Amazon RDS) to take advantage of discounted pricing.
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AWS
aws.amazon.com › amazon ec2 pricing › reserved instances › pricing
EC2 Reserved Instance Pricing
3 days ago - With the Partial Upfront option, you make a low upfront payment and are then charged a discounted hourly rate for the instance for the duration of the Reserved Instance term. The No Upfront option does not require any upfront payment and provides a discounted hourly rate for the duration of the term. Notice: Red Hat has made an update to their cloud pricing model for Red Hat Enterprise Linux (RHEL). On July 1, 2024 pricing for EC2 RHEL changed to a per-vCPU-hour based pricing model. Learn about the new prices in the RHEL on AWS Pricing page.
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CloudZero
cloudzero.com › home › blog › aws reserved instances 101: the complete guide
AWS Reserved Instances 101: The Complete Guide
August 25, 2025 - Reserved instances and on-demand instances have the same compute options and configurations. “All you’re doing is committing to use in return for a lower hourly rate, which AWS will apply to your bill after the month ends, depending on the instances that best fit your workload,” explains Miller.
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Godparticleit
godparticleit.com › mastering-aws-reserved-instances-for-cost-savings
Mastering AWS Reserved Instances for Cost Savings — God Particle IT Group
August 30, 2023 - Reserved Instances allow you to reserve capacity for your applications and save substantially compared to running instances on-demand, in exchange for a term commitment. AWS Reserved Instances provide several key benefits:
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Densify
densify.com › home › what are amazon reserved instances?
What are Amazon Reserved Instances?
April 13, 2023 - RIs are a reservation of resources and capacity—not a physical instance type—and manifest as a billing discount or coupon applied against On-Demand instance use in an AWS account.