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Tutorials › AWS Solutions Architect › S3 — Simple Storage Service

S3 — Simple Storage Service

5 min read Quiz at the end
Master S3 storage classes, security features, versioning, and lifecycle policies. S3 is tested heavily on the SAA-C03 exam.

S3 — Unlimited Object Storage

S3 stores files (called objects) in containers (called buckets). It is infinitely scalable, globally accessible, and 11 nines (99.999999999%) durable. Think of S3 as a hard drive in the cloud with unlimited capacity.

Teacher Note: Imagine S3 is a giant filing cabinet in the cloud. You can put any file in it — photos, videos, database backups, application logs. You can share files with anyone, or keep them completely private. The filing cabinet never gets full.

S3 Storage Classes — Pay for What You Actually Need

Storage ClassRetrieval SpeedCostBest For
S3 StandardMilliseconds$0.023/GBFrequently accessed: websites, app data
S3 Intelligent-TieringMillisecondsAuto-optimisedUnknown access patterns — auto-moves objects
S3 Standard-IAMilliseconds (+ retrieval fee)$0.0125/GBBackups, DR — accessed monthly
S3 One Zone-IAMilliseconds (+ retrieval fee)$0.01/GBReproducible data — lower redundancy
S3 Glacier InstantMilliseconds$0.004/GBArchives accessed quarterly
S3 Glacier Flexible1-12 hours$0.0036/GBArchives accessed 1-2 times per year
S3 Glacier Deep Archive12-48 hours$0.00099/GB7-10 year compliance archives — cheapest!

Critical S3 Security Rules

  • Block Public Access: DEFAULT ON since 2023 — prevents accidental public exposure
  • Bucket Policies: JSON rules controlling who can access what (cross-account, public websites)
  • Versioning: keeps ALL versions of every file — accidental delete creates a delete marker, not permanent deletion
  • MFA Delete: requires MFA to permanently delete versioned objects
  • Object Lock: WORM protection — compliance mode means even root account cannot delete until expiry

S3 Key Features

# S3 Use Cases
Static Website Hosting     -- HTML, CSS, JS served directly from S3
Data Lake                  -- Store Parquet files for Athena queries
Backup and DR              -- Automated daily backups from RDS, EC2
Content Distribution       -- Origin for CloudFront CDN
Event-Driven Processing    -- S3 upload triggers Lambda function

# S3 Performance
Per prefix: 3,500 PUT/s + 5,500 GET/s
For high throughput: use multiple key prefixes
For large files: use Multipart Upload (>100MB)
Exam Tip: S3 is GLOBAL but buckets are REGIONAL. Know the storage classes by access pattern: frequent = Standard, infrequent = IA, rare = Glacier, never = Deep Archive. The exam loves S3 security — Block Public Access overrides ALL other settings.
Topic Quiz · 3 questions

Test your understanding before moving on

1. A company must store compliance documents for 7 years and retrieve them rarely. Which S3 storage class minimises cost?
💡 S3 Glacier Deep Archive at $0.00099/GB is the cheapest storage on AWS — designed for 7-10 year compliance archives.
2. A developer accidentally deleted an important file from S3. Which S3 feature would allow recovery?
💡 S3 Versioning keeps all versions of every object — a delete operation creates a delete marker, and previous versions are recoverable.
3. Which S3 feature automatically moves objects to cheaper storage classes based on access patterns without human intervention?
💡 S3 Intelligent-Tiering monitors access patterns and automatically moves objects between tiers without performance impact or retrieval fees.