4.2 Storage Cost Optimization — S3 Tiers, EBS, and Data Transfer

AWS Solutions Architect Associate SAA-C03

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1 Introduction

About the AWS Solutions Architect Associate (SAA-C03) Exam Study Strategies and Exam Tips for SAA-C03 The AWS Well-Architected Framework

2 Domain 1: Design Secure Architectures (30%)

1.1 IAM Fundamentals — Users, Groups, Roles, and Policies 1.2 AWS Organizations, SCPs, and Multi-Account Strategy 1.3 VPC Security — Security Groups, NACLs, and VPC Endpoints 1.4 Encryption, KMS, and Secrets Management 1.5 AWS WAF, Shield, and Network Firewall 1.6 GuardDuty, Inspector, Macie, and Security Hub 1.7 The Shared Responsibility Model for Solutions Architects 1.8 Data Protection, Compliance, and Audit Services

3 Domain 2: Design Resilient Architectures (26%)

2.1 Elastic Load Balancing (ELB) — ALB, NLB, and GWLB 2.2 EC2 Auto Scaling — Dynamic, Predictive, and Scheduled 2.3 Multi-AZ and Multi-Region Architectures 2.4 Disaster Recovery Strategies — RTO and RPO 2.5 Decoupling with SQS, SNS, and EventBridge 2.6 AWS Step Functions and Workflow Orchestration

4 Domain 3: Design High-Performing Architectures (24%)

3.1 EC2 Instance Types, Purchasing Options, and Placement Groups 3.2 Lambda, Serverless Compute, and Container Services 3.3 Amazon S3 - Storage Classes, Lifecycle, and Performance 3.4 Block and File Storage - EBS, EFS, and FSx 3.5 Database Services - RDS, Aurora, DynamoDB, and More 3.6 CloudFront, Route 53, and Global Accelerator 3.7 Data Ingestion and Transformation - Kinesis, Glue, and EMR

5 Domain 4: Design Cost-Optimized Architectures (20%)

4.1 Compute Cost Optimization — Right-Sizing, RIs, Savings Plans, and Spot 4.2 Storage Cost Optimization — S3 Tiers, EBS, and Data Transfer 4.3 Database Cost Optimization 4.4 AWS Cost Management and Monitoring Tools

6 VPC and Networking Deep Dive

5.1 VPC Architecture — Subnets, Route Tables, and Gateways 5.2 VPC Connectivity — Peering, Transit Gateway, and Direct Connect 5.3 Amazon API Gateway 5.4 CloudFormation and Infrastructure as Code 5.5 AWS PrivateLink and Endpoint Services

7 Migration, Transfer, and Hybrid Services

6.1 The 7 Rs of Cloud Migration 6.2 AWS Snow Family — Snowball Edge Devices 6.3 CloudWatch, CloudTrail, and AWS Config 6.4 Amazon Cognito and Identity Federation 6.5 AWS DataSync and Transfer Family

8 Serverless Architecture and Application Services

7.1 Serverless Architecture Patterns 7.2 Advanced SQS Patterns — DLQ, Backpressure, and FIFO 7.3 Analytics Services — Athena, OpenSearch, and QuickSight 7.4 Container Orchestration — ECS, EKS, and ECR

9 Advanced Topics and Exam Scenarios

8.1 Advanced IAM — Permission Boundaries, Federation, and Cross-Account 8.2 Caching Strategies and ElastiCache Patterns 8.3 Hybrid Architecture — DNS, Storage, and Compute 8.4 SAA-C03 Scenario Practice — Putting It All Together

4.2 Storage Cost Optimization — S3 Tiers, EBS, and Data Transfer

Key Takeaways Explain This Topic AI

S3 lifecycle policies automate transitions to colder classes; moving Standard to Glacier Deep Archive cuts storage cost by about 95%.

S3 Intelligent-Tiering moves objects between tiers automatically for a small per-object monitoring fee — the answer when access patterns are unknown.

gp3 is about 20% cheaper than gp2 and decouples IOPS/throughput from size; st1/sc1 HDD volumes are far cheaper for large sequential workloads.

Ingress is always free; cross-AZ is $0.01/GB each way, cross-Region about $0.02/GB, and internet egress starts at $0.09/GB.

S3 and DynamoDB Gateway VPC Endpoints are free and bypass NAT Gateway data-processing charges of $0.045/GB.

Last updated: October 2026

S3 Storage Class Costs and Retrieval

S3 storage classes trade price per GB against retrieval latency, retrieval cost, and minimum durations. Approximate us-east-1 prices:

• Storage class $/GB-month Min duration Retrieval
• S3 Standard 0.023 none instant, free
• Intelligent-Tiering 0.023 → 0.0036 none instant; small monitoring fee/object
• Standard-IA 0.0125 30 days instant; per-GB retrieval fee
• One Zone-IA 0.01 30 days instant; single-AZ durability
• Glacier Instant Retrieval 0.004 90 days milliseconds
• Glacier Flexible Retrieval 0.0036 90 days minutes to 12 hr
• Glacier Deep Archive 0.00099 180 days within 12 hr (Standard) or 48 hr (Bulk)

Moving Standard → Deep Archive saves about 95.7% per GB. Watch the minimum-duration trap : deleting an IA or Glacier object early still bills the full 30/90/180-day minimum, so short-lived data belongs in Standard.

Choosing a Tiering Strategy

• Situation Correct answer
• Known, predictable age-out (e.g., logs) Lifecycle policy with explicit transitions
• Unknown/changing access pattern Intelligent-Tiering (no retrieval fees)
• Reproducible data, can tolerate single AZ One Zone-IA
• Compliance archive, retrieval rare and slow Glacier Deep Archive

Lifecycle rules also expire noncurrent versions and abort incomplete multipart uploads (commonly after 7 days) — a frequent source of silent storage waste. Use S3 Storage Class Analysis to discover when to transition, and Requester Pays so downloaders, not the bucket owner, pay egress on shared datasets.

EBS Cost Optimization

• Action Savings
• Migrate gp2 → gp3 ~20% cheaper; set IOPS/throughput independently
• Use st1 / sc1 HDD Far cheaper for large sequential throughput (big-data, logs)
• Delete orphaned volumes 100% — unattached volumes still bill
• Prune old snapshots with DLM Amazon Data Lifecycle Manager automates creation/cleanup
• Right-size over-allocated volumes You pay for provisioned size, not used
• Data Transfer Charges

• Transfer Cost
• Internet into AWS (ingress) Free
• Same AZ via private IP Free
• Cross-AZ, same Region $0.01/GB each way
• Cross-Region ~$0.02/GB
• Internet egress from $0.09/GB
• Via CloudFront ~$0.085/GB + caching cuts origin hits
• S3/DynamoDB Gateway Endpoint Free

On the Exam: "Cut data-transfer cost from EC2 to S3" → S3 Gateway VPC Endpoint (free, bypasses NAT). "Reduce NAT Gateway bill" → route AWS-service traffic through VPC endpoints. "Lower egress to global users" → CloudFront.

Hybrid Storage with Storage Gateway

• Gateway type Protocol → backend Use case
• S3 File Gateway NFS/SMB → S3 File shares, data-lake ingest
• FSx File Gateway SMB → FSx for Windows Cached Windows shares
• Volume Gateway iSCSI → S3 + EBS snapshots Block storage, DR
• Tape Gateway VTL → S3 Glacier Replace physical backup tape

Storage Gateway keeps a hot local cache while tiering the bulk of data to low-cost S3/Glacier — the standard answer for "reduce on-prem storage cost without a full migration."

Worked Example: Lifecycle vs. Intelligent-Tiering

A media company stores rendered video. Editors access a clip heavily for its first month, occasionally for a year, then almost never. Because the access pattern is known and time-based , a lifecycle policy is the cheaper answer: Standard for 30 days, Standard-IA at 30 days, Glacier Flexible at 365 days, and Deep Archive beyond two years. Intelligent-Tiering would also work but charges a small per-object monitoring fee that is pure waste when the decay curve is already predictable.

Flip the scenario — a data-science bucket where any object might suddenly become hot — and Intelligent-Tiering wins, because it moves objects between frequent and infrequent tiers automatically with no retrieval fees and no guessing.

A second worked example exposes the minimum-duration trap . A team writes temporary export files and deletes them after 5 days. Moving these to Standard-IA looks cheaper per GB, but IA bills a 30-day minimum per object, so deleting at day 5 still incurs 30 days of charges plus a per-GB retrieval fee on read — net more expensive than leaving them in Standard. Short-lived objects belong in Standard; only data that genuinely ages past the minimum duration benefits from colder classes.

EBS and Snapshot Cost Detail

EBS volumes bill on provisioned capacity, not used bytes, so a 1 TB gp3 volume holding 100 GB still bills for 1 TB. Migrating gp2 → gp3 is almost always free money: gp3 starts cheaper per GB and includes a baseline 3,000 IOPS and 125 MB/s independent of size, so you stop over-provisioning size just to buy throughput. For large sequential workloads — log processing, big-data scans — st1 (throughput-optimized HDD) and sc1 (cold HDD) are dramatically cheaper than SSD because the access pattern does not need low-latency random IOPS.

Snapshots are incremental but accumulate silently. Use Amazon Data Lifecycle Manager (DLM) to schedule creation and automatic deletion against a retention policy rather than relying on manual cleanup. The exam's cost-optimization framing here is: find and delete orphaned volumes (unattached but still billing 100%), prune stale snapshots with DLM, and right-size over-allocated volumes.

On the Exam: "Cheapest EBS for large sequential big-data reads" → st1. "Lower EBS cost with no performance loss" → gp2 to gp3. "Automate snapshot retention" → Data Lifecycle Manager.

Storage-Cost Trap Table

• Tempting wrong answer Why it fails
• IA/Glacier for objects deleted within days Minimum-duration billing exceeds Standard cost
• Intelligent-Tiering with a known decay curve Unneeded per-object monitoring fee
• Transfer Acceleration to "cut transfer cost" It adds a premium; it speeds long-distance uploads
• Sizing an EBS volume up just for more IOPS gp3 sets IOPS/throughput independently of size
• Leaving detached volumes "just in case" Unattached volumes still bill at 100%