AWS for DevOps — Reserved & Savings Plans

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14.3 — Reserved Instances & Savings Plans

If you have predictable workloads, committing to 1 or 3 years can save 30-60%.

Reserved Instances (RI)

Reserved Instances are a billing discount applied to On-Demand usage that matches the RI attributes.

Payment Option Discount (1 yr) Discount (3 yr)
No Upfront ~30% ~40%
Partial Upfront ~35% ~50%
All Upfront ~40% ~60% 
# Check RI recommendations
$ aws ce get-reservation-purchase-recommendation \
    --service "Amazon Elastic Compute Cloud - Compute" \
    --term-in-years ONE_YEAR \
    --payment-option NO_UPFRONT \
    --lookback-period-in-days SIXTY

RI Types

Type Flexibility Discount Best For
Standard Fixed instance type/region Highest Stable workloads
Convertible Can change instance family Lower Workloads that may evolve

Savings Plans

Savings Plans are more flexible than RIs. You commit to a $/hour spend, and AWS applies the discount to any matching usage.

Plan Type Applies To Flexibility
Compute Savings Plan EC2, Fargate, Lambda Any instance family, size, region, OS
EC2 Instance Savings Plan EC2 only Specific instance family + region 
# Check Savings Plan recommendations
$ aws ce get-savings-plans-purchase-recommendation \
    --savings-plans-type COMPUTE_SP \
    --term-in-years ONE_YEAR \
    --payment-option NO_UPFRONT \
    --lookback-period-in-days SIXTY

Reserved vs Savings Plans

Feature Reserved Instances Savings Plans
Applies to EC2, RDS, ElastiCache, etc. EC2, Fargate, Lambda
Flexibility Instance type specific Any instance type
Region lock Standard: yes Compute SP: no
Discount Slightly higher Slightly lower
Recommendation Specific known workloads General compute commitment

Decision Framework

  Do you have predictable compute usage?
  │
  ├── YES → Do you know the exact instance types?
  │         │
  │         ├── YES → Reserved Instances (Standard)
  │         │         Highest discount
  │         │
  │         └── NO → Savings Plans (Compute)
  │                   Flexible across instance types
  │
  └── NO → On-Demand + Spot + Auto-Scaling
            Pay for what you use

Common Mistakes

Mistake Why It Hurts Fix
Buying RIs without usage analysis May not match actual usage Use Cost Explorer recommendations first
All 3-year commitments Locked in if needs change Mix 1-year and 3-year terms
Not reviewing RI utilization Paying for unused reservations Check monthly in Cost Explorer
RIs for volatile workloads Poor utilization Use Savings Plans or Spot instead

Next → Spot Instances

Updated:

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