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RDS SQL Server Running Bundled Licensing on Older Instance Families

The short version

Amazon RDS for SQL Server has traditionally used a License Included model where the SQL Server license cost is bundled into a single hourly instance price alongside Windows OS licensing, compute resources, and RDS management capabilities.

Balazs Engedi

FinOps Specialist @ KPN

AWS service
AWS RDS
Category
Databases
Reference
CER-0323
Type
Suboptimal Pricing Model

Explanation

Why the waste happens and who it affects.

On older generation instance families such as db.R6i, db.M6i, db.R5, and db.M5, this bundled rate offers no visibility into how much of the hourly cost is attributable to licensing versus infrastructure - and the licensing component can represent a substantial portion of the total charge, especially for Standard and Enterprise editions.

Starting with 7th generation instances (db.M7i and db.R7i, and since extended to db.M8i, db.R8i, db.M8a and db.R8a), AWS introduced an unbundled pricing model that separates infrastructure costs from SQL Server licensing fees, billing them as distinct line items. This structural change can yield significantly lower total costs compared to equivalent previous-generation instances. Additionally, the unbundled model enables the Optimize CPU feature, which by default disables SMT on instances with 2 or more physical cores, halving the vCPU count - and therefore licensing charges - while keeping all physical cores, memory, and IOPS capacity. On 2xlarge and larger sizes, customers can lower the core count further (to a minimum of 4 vCPUs) for additional licensing savings, which reduces the number of active physical cores. This is particularly valuable for memory-intensive or IOPS-intensive SQL Server workloads that don't need high vCPU counts but were previously forced to pay for licensing on all provisioned vCPUs.

Organizations running RDS SQL Server on older instance families continue to pay the higher bundled rate unnecessarily. The savings opportunity compounds in Multi-AZ deployments and on larger instance sizes (2xlarge and above, where the core count can also be customized). Hyperthreading is disabled by default on 7th generation instances with 2 or more physical cores, effectively halving the vCPU count and the associated licensing fees without sacrificing physical core performance.

Billing model

The pricing dimensions that drive this cost.

RDS for SQL Server instances are billed per-second with a 10-minute minimum charge following any billable status change. The hourly rate encompasses multiple cost components, and the billing structure differs between instance generations:

  • Older generations (db.R6i, db.M6i, db.R5, db.M5, etc.): A single bundled hourly rate that includes SQL Server licensing, Windows OS licensing, compute, and RDS management - with no breakdown of individual cost components.
  • 7th generation and newer (db.M7i, db.R7i, db.M8i, db.R8i, db.M8a, db.R8a): An unbundled model where the instance price is billed per CPU hour and SQL Server licensing is billed separately per vCPU hour, providing full cost transparency in billing line items.

Under the unbundled model, licensing fees are not eligible for AWS organizational discounts, though the infrastructure component remains eligible. Storage and I/O charges are billed separately regardless of instance generation. The unbundled pricing on db.M7i and db.R7i instances can deliver up to 55% lower costs compared to equivalent previous-generation instances, primarily through reduced licensing charges. For current rates, see Amazon RDS for SQL Server Pricing.

How to detect

6 checks to find it in your estate.

  • Identify all RDS SQL Server instances (db.R6i, db.M6i, db.R5, db.M5, or earlier generations) running Standard or Enterprise editions on instance families.
  • Review instance sizes to prioritize migration candidates - assess which instances are 2xlarge or larger, where the licensing savings from unbundled pricing and reduced vCPU counts are most significant.
  • Evaluate deployment configurations to identify Multi-AZ instances, where licensing optimization on 7th generation instances yields compounded savings.
  • Assess whether existing workloads are memory-intensive or IOPS-intensive rather than CPU-bound, as these benefit most from the Optimize CPU feature available on db.M7i, db.R7i, db.M8i, db.R8i, db.M8a, and db.R8a instances.
  • Review any active Reserved Instance commitments tied to older instance families to understand contractual obligations that may affect migration timing (RDS reserved DB instances cannot be cancelled, and RDS for SQL Server reservations are not size-flexible)
  • Confirm the SQL Server edition and version in use to ensure compatibility with the target 7th generation instance class.

How to fix

6 ways to remove the waste.

  • Migrate eligible RDS SQL Server instances from older generation families (db.R6i, db.M6i, db.R5, db.M5, etc.) to the equivalent unbundled instance class (db.M7i, db.R7i, db.M8i, db.R8i, db.M8a or db.R8a) to take advantage of unbundled licensing and lower total costs.
  • After migrating to a 7th generation instance, evaluate the Optimize CPU feature to customize the core count on 2xlarge and larger sizes - reducing licensing charges for workloads that do not require the full default vCPU allocation while retaining the same memory and IOPS (a lower core count means fewer active physical cores).
  • For instances with active Reserved Instance commitments on older families, plan migrations to coincide with RI expiration dates.
  • Consider purchasing Database Savings Plans or Reserved Instance for the new 7th or 8th generation instances to achieve additional savings with commitment-based discounts.
  • Prioritize migration of the largest instances and Multi-AZ deployments first, as these represent the highest absolute savings from unbundled licensing.
  • Validate application performance after migration, particularly for workloads where hyperthreading behavior changes on 7th generation instances (disabled by default on sizes with 2 or more physical cores) may affect CPU-bound operations.

Documentation

Vendor references for pricing and configuration.

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