I'm trying to verify the correct hourly commitment for an AWS RDS Savings Plan. I have one db.r8i.2xlarge RDS instance running Windows with SQL Server continuously.
The current On-Demand costs are:
- Instance compute: $1.20/hour
- Windows license: $0.184/hour
- SQL Server license: $0.48/hour
- Total: $1.864/hour
With the Savings Plan, the compute portion would be reduced to $0.96/hour, while the licensing charges remain unchanged:
- Discounted compute: $0.96/hour
- Windows license: $0.184/hour
- SQL Server license: $0.48/hour
- Total after the discount: $1.624/hour
I initially assumed the commitment should therefore be $1.624/hour. However, the AWS Purchase Analyzer recommends a commitment of $0.96/hour and estimates savings of about $175.02 per month, or 20%.
Is the commitment supposed to cover only the discounted compute amount, or should it include the total RDS cost after adding the Windows and SQL Server licenses? I'd especially appreciate confirmation from anyone using a Savings Plan with SQL Server on RDS.
3 Answers
Think of it as two separate meters. You commit $0.96/hour toward eligible RDS compute usage, while the $0.184 Windows charge and $0.48 SQL Server charge are billed on top at standard pricing. Committing to $1.624/hour would overcommit, because the license costs are not covered by the plan.
The analyzer is correct: the commitment covers only the RDS compute portion, so $0.96 per hour is the appropriate commitment in this example. The Windows and SQL Server license charges are separate and remain at their regular rates.
The recommendation assumes the instance’s compute usage is stable. If this is your only RDS workload and it really runs continuously, covering the expected compute usage should be reasonable. Before purchasing, still verify the plan’s scope and coverage assumptions for the relevant instance family and Region.
Related Questions
Can't Load PhpMyadmin On After Server Update
Redirect www to non-www in Apache Conf
How To Check If Your SSL Cert Is SHA 1
Windows TrackPad Gestures