Object Storage (S3 & Azure Blob)
maang.io System Design Series
Object storage (Amazon S3, Azure Blob) keeps data as objects — a blob plus rich metadata — in a flat namespace addressed by key, not a file tree. It trades filesystem semantics for near-infinite scale and eleven-nines durability via replication/erasure coding. It's the substrate under data lakes, backups, static hosting, and big-data pipelines.
This deep dive comes in three parts:
- Foundations & Core Concepts — objects vs block/file storage and the key-based model.
- Internals — durability, consistency, storage tiers, and multipart upload, with worked numbers.
- Interview — Staff/Principal Q&A: when object storage fits and its consistency guarantees.