Aliases: S3, Blob storage, Bucket
Object Storage
Cloud storage that keeps files as objects in flat buckets accessed over HTTP — cheap, effectively unlimited, and the backbone of cloud data.
What is object storage?
Object storage stores data as objects — the file bytes plus metadata plus a key — in flat containers called buckets, accessed via HTTP APIs rather than mounted filesystems. Amazon S3 defined the model; Google Cloud Storage, Azure Blob Storage, and S3-compatible systems (Cloudflare R2, MinIO) followed. It scales to exabytes with 11-nines durability and pennies-per-GB pricing.
Object vs block vs file
| Type | Looks like | Best for |
|---|---|---|
| Object | HTTP API + keys | Backups, media, data lakes, static sites, ML datasets |
| Block | A raw disk attached to one VM (EBS) | Databases, boot volumes — anything needing a filesystem |
| File | A shared network drive (EFS, NFS) | Legacy apps, shared home directories |
Objects are immutable — you replace, not edit — and there are no real directories, just key prefixes that look like paths.
Storage classes and lifecycle
Providers tier by access frequency: hot (standard) → infrequent access → archive (Glacier-class, hours to retrieve). Lifecycle rules move objects between tiers automatically — the difference between a data lake that costs 400.
Cost reality
The sticker price (~0.09/GB on major clouds — moving 100 TB out is ~$9k, which is R2’s whole zero-egress pitch), request charges on millions of small objects, and cross-region transfer. Design rule: process data in the region where it lives.
What people get wrong
- Public buckets. The classic cloud breach; default-deny, use presigned URLs for sharing, audit with provider tools.
- Using it as a filesystem. Listing “directories” with millions of keys and rewriting objects for small edits fights the model; that workload wants block or file storage.
- Ignoring lifecycle from day one. Data accumulates forever by default — the bill only goes up until you add rules.
Historical figures and technical concepts for informational purposes only. Not technical, professional, legal, or financial advice. Sources: Official Documentation.