How to Reduce Amazon RDS Costs with Reserved Instances

Share this Post

In our earlier article we reviewed the different types of relational database instances to help you configure your AWS infrastructure to meet the needs of your database applications. In this article we will explain how you can reduce the cost of Amazon RDS with Reserved Instances. For Amazon Redshift pricing you can read our earlier article.

Amazon RDS is a managed service that runs database servers on EC2 instances which  bills for compute time. RDS DB instance types, such as db.m5.large, correspond to similar EC2 instance types, such as m5.large, yet they cost significantly more than their EC2 equivalents. Using reserved capacity for longer-term commitments can help you lower costs while minimizing risk.

What are the different terms and payment options for RDS?

  • On-demand pricing lets you pay only for the db instances that you use, with no up-front commitment.
  • Reserved Instances provide up to 60% discount compared to on-demand rates when you commit to a set number of DB instances over one or three years. Reserved Instances are the only volume discount pricing model for database services, as Savings Plans are not available for Amazon RDS. Reserved DB Instance pricing does not cover storage or I/O costs, which are charged separately.

Amazon RDS Reserved Instances are available in three payment options:

  • All Upfront: This option lets you pay all of the Reserved DB Instance fees upfront, and as a result provides the largest discount compared to on-demand pricing.
  • Partial Upfront: This option lets you pay a portion of the upfront payment. You will then be charged the discounted rate for the duration of the Reserved Instance term.
  • No Upfront: With this option you don’t have to pay any fees upfront, but pay for the discounted hourly rate for the duration of the term. This option provides the smallest discounts and is only available for one year term.

Why should you use reserved over on-demand instances?

Amazon RDS Reserved Instances provide up to 60% discount over on-demand rates, and are ideal for the following applications:

  • Steady state use cases
  • Production environments that require database servers to be available 24×7
  • Mission critical applications that run on Multi Availability Zone database deployments

In addition to use cases and application needs, you can determine whether Reserved DB Instances are a good fit by comparing on-demand hourly rates to the effective hourly rate for Reserved Instances. The effective hourly rate is the one-time fee amortized over the term of the RI, plus the hourly usage rate.

The automated cost optimization tool by Parquantix monitors Amazon RDS Reserved Instance usage and manages all RIs in real time. To find out more, contact us for a consultation.

Amazon RDS Reserved Instances are available for all DB Engines supported by AWS, including Amazon Aurora, PostgreSQL, MySQL, MariaDB, Oracle, and Microsoft SQL Server.

How does RDS pricing differ by database engine?

Each database engine supported by AWS has different options for licensing, instance size flexibility and redundancy that affect pricing. You should review the pros and cons of each dbase engine to determine total cost.

RDS Instance Size Flexibility

Unlike Amazon EC2, RDS does not support convertible reserved instances. However, RDS RIs offer size flexibility for the following database engines: MySQL, MariaDB, PostgreSQL, Amazon Aurora and Oracle (BYOB – Bring Your Own License edition). This means that the discounted RI rate will apply to usage of any size in the same instance family. For example, a db.m5.2xlarge MySQL RI can be automatically applied to 2 db.m5.xlarge instances.

Licensing Models

Amazon RDS supports three licensing models: • License included: The software license fee is included when you set up an Amazon RDS DB instance for Microsoft SQL Server. • Bring your own license (BYOL): The license you purchased can be used to set up RDS DB instances for engines such as Oracle BYOL edition • No license fee: MySQL, MariaDB, PostgreSQL and Aurora have no licensing fees

Database Engines Supported by Amazon RDS

Following is an overview of the database engines that are supported by Amazon RDS to help you evaluate the pricing implications:

Amazon Aurora is a cloud-native relational database, fully managed by Amazon RDS. It runs significantly faster than the compatible MySQL and PostgreSQL standard databases at a fraction of the cost.

MySQL, MariaDB and PostgreSQL are open source relational databases that are cost-efficient.

Microsoft SQL Server as a 3rd party software tends to cost more than all other database engines. However the license is Included in Amazon RDS, and therefore does not incur additional licensing fees.

Oracle has two different licensing models – “License Included” and “Bring-Your-Own-License (BYOL)”. In the “License Included” model, AWS has already licensed Oracle Database software, which eliminates the need to purchase separate licenses.

The table below illustrates sample pricing for db.r5.large across different database engines in US East (N. Virginia). Microsoft SQL Server has the highest hourly cost of all dbase engines supported by AWS.

Stop and Start

In addition to discount pricing options, setting stop and start rules for your database instances can also provide substantial savings. If your database is not required to run 24/7, it can be stopped for up to 7 days at a time. This is a viable and affordable option for Amazon RDS with variable usage patterns and for databases in development and testing environments.

Optimize Your Database Utilization with an Automated Tool

Compared to other AWS services, Amazon RDS instance pricing has additional complexity based on the database engines that you use for your applications, related variations along licensing and software editions, and extra storage and I/O charges. Compounding these factors are the limitations for 1 year terms for no upfront payments and the lack of sales capability in the AWS Marketplace. Your reserved dbase instances can present risks and extra costs that can overwhelm your investment in the cloud.

The time and effort associated with constantly monitoring and analyzing your usage, and with purchasing reserved db instances to modify and apply to actual usage, present ongoing challenges to managing your AWS infrastructure costs. Fortunately, you can take full advantage of the powerful automated tool that Parquantix offers to simplify all the resource procurement, monitoring, analysis and management, while realizing substantial savings. With a tool that does it all for you, you can focus on what matters most: Building and running applications in the cloud to drive growth for your business.

Are you ready to optimize the cost of your applications on Amazon RDS?

Contact us to schedule a 30-minute consultation:
  • This field is for validation purposes and should be left unchanged.