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AWS Solutions Architect · Lesson

Cost Optimisation and Sustainability Pillars

Adopt expenditure awareness, matched resource sizing, and pricing model selection for cost; minimise infrastructure footprint and improve energy efficiency for sustainability.

Cost Optimisation Pillar Overview

The Cost Optimisation pillar focuses on avoiding unnecessary costs and getting the most value from your AWS spending. It is often the most immediately impactful pillar because cloud resources are easy to over-provision. Key design principles: Implement cloud financial management — treat cost as a first-class metric. Adopt a consumption model — pay only for what you use. Measure overall efficiency — track cost per unit of business value. Reduce spending on undifferentiated heavy lifting — use managed services instead of managing infrastructure.

# Cost Optimisation pillars:
# 1. Expenditure awareness  - visibility into what you spend
# 2. Cost-effective resources - right instance types, storage classes
# 3. Matching supply to demand - auto scaling, spot instances
# 4. Optimising over time - regularly review and adjust

# Example: undifferentiated heavy lifting
# Instead of managing your own Redis: use ElastiCache
# Instead of managing Kubernetes: use EKS or Fargate
# Managed services reduce operational overhead AND cost

Right-Sizing Resources

Right-sizing is the most impactful cost optimisation action — identifying and eliminating over-provisioned resources. A common pattern is launching large instances during initial provisioning and never revisiting them. AWS Compute Optimizer analyses utilisation metrics and recommends the optimal instance type. Common finding: an m5.4xlarge running at 5% CPU should be a t3.medium, saving 80% of compute cost. Right-sizing applies to EC2, Lambda (memory), RDS, and EBS volumes.

# Get Compute Optimizer recommendations for all EC2
aws compute-optimizer get-ec2-instance-recommendations \
  --filters Name=finding,Values=Overprovisioned

# Response includes:
# currentInstanceType: m5.4xlarge
# recommendedInstanceType: t3.large
# estimatedMonthlySavings: $280
# performanceRisk: VeryLow

# Also check EBS volumes:
aws compute-optimizer get-ebs-volume-recommendations \
  --filters Name=finding,Values=Overprovisioned

All lessons in this course

  1. Operational Excellence and Security Pillars
  2. Reliability and Performance Efficiency Pillars
  3. Cost Optimisation and Sustainability Pillars
  4. Well-Architected Tool and Review Process
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