Cutting SQL Server costs on AWS: editions, Optimize CPUs, instance choice, consolidation and Babelfish

#1. Know where the money goes

For license-included SQL Server, the SQL licence portion of the hourly price is usually larger than the compute. That's why core count — not instance size — is the main lever.

# EC2 instances running SQL Server license-included AMIs (usage operation codes)
aws ec2 describe-instances --query "Reservations[].Instances[].[InstanceId,InstanceType,UsageOperation]" --output table

RunInstances:0102 (Windows + SQL Enterprise), :0006 (Standard), :0202 (Web) — check AWS's billing codes list.

#2. Edition review: Enterprise → Standard

Many databases on Enterprise don't use Enterprise-only features.

SELECT feature_name FROM sys.dm_db_persisted_sku_features;   -- run in each database

Empty result = no Enterprise-only features persisted in that database. Also check instance-level needs: memory (> 128 GB buffer pool), cores (> 24), AGs with readable secondaries, online index rebuilds. Standard with Basic AGs or RDS Multi-AZ covers many HA needs.

#3. Optimize CPUs (EC2)

Choose instances with lots of memory per core and turn off cores you don't need:

aws ec2 run-instances --instance-type r7i.4xlarge \
  --cpu-options "CoreCount=4,ThreadsPerCore=2" ...

8 vCPUs instead of 16 → half the SQL licence cores, same 128 GB memory. Benchmark first: for memory-bound workloads the difference is small.

Instance families like x2iedn and r7iz are popular for this (high memory or high clock per core).

#4. Consolidate

• Many small instances each with 4-core minimums → fewer, bigger instances (or multiple databases per RDS instance).
• Check isolation needs (noisy neighbours, maintenance windows, security boundaries) before merging.

#5. Commitments

• Savings Plans / Reserved Instances for EC2 and RDS (RDS RIs apply to the license-included price).
• BYOL (where your licensing allows) can be cheaper with SA License Mobility — compare with license-included including SA cost.

#6. Non-production

• Developer edition (free) for dev/test on EC2 — never license-included Enterprise for dev.
• Schedule non-prod instances to stop out of hours (Instance Scheduler on AWS).

#7. Refactor where it pays: Babelfish / PostgreSQL

Removing SQL Server entirely (Aurora PostgreSQL + Babelfish, or native PostgreSQL) removes the licence. It pays off for apps you own with moderate T-SQL complexity — see the Babelfish post. Do the cheaper levers above first.

#8. Track it

Tag every SQL resource (app, env, edition, licenceModel), use Cost Explorer grouped by usage type, and review monthly.

Tip

Check sys.dm_db_persisted_sku_features across the estate early. Teams are often surprised that most of their "Enterprise" databases could run on Standard, which roughly quarters the licence price per core.