What is Amazon S3?
Amazon Simple Storage Service (Amazon S3) is an object storage service. It stores data as objects within buckets. It is designed for 99.999999999% (11 9s) of durability. It is the backbone of data storage on AWS.
Key Concepts
1. Buckets & Objects
- Bucket: A container for objects. Names must be globally unique across all AWS accounts.
- Object: A file and any metadata that describes that file. S3 is a flat structure (no real folders, just prefixes).
2. Storage Classes (Exam Critical)
- S3 Standard: General purpose, frequently accessed data.
- S3 Intelligent-Tiering: Automatically moves data between tiers based on changing access patterns. No retrieval fees.
- S3 Standard-IA (Infrequent Access): For data accessed less often but requires rapid access when needed. Lower storage cost, but you pay a retrieval fee.
- S3 One Zone-IA: Stores data in a single Availability Zone (AZ). cheaper, but less resilient (data lost if AZ fails).
- S3 Glacier Instant Retrieval: Millisecond access for archives.
- S3 Glacier Flexible Retrieval: Retrieval times from minutes to hours.
- S3 Glacier Deep Archive: Lowest cost. Retrieval within 12 hours.
3. Security
- Block Public Access: Enabled by default on new buckets. Prevents accidental public exposure.
- Versioning: Keys to protecting against accidental deletes. Keeps multiple variants of an object.
- Encryption: Supports Server-Side Encryption (SSE-S3, SSE-KMS, SSE-C) and Client-Side Encryption.
Exam Tips
[!IMPORTANT] S3 is for Objects (Files), NOT Blocks (OS/Boot Drives). You cannot install an Operating System on S3. That is for EBS.
[!WARNING] If a question asks about "Globally available storage for static website hosting," the answer is usually S3.
Common Use Cases
- Backup and archive.
- Data lakes and big data analytics.
- Hosting static websites (HTML/CSS/JS).
- Disaster recovery.