Lesson 4 of 7 · 9 min
Storage: object, block and file
Pick between S3, EBS and EFS on access pattern, and use storage classes without getting caught by minimums.
The three kinds
| Type | Service | Access | Use when |
|---|---|---|---|
| Object | S3 | HTTP API, flat key namespace | Files, backups, static assets, data lakes |
| Block | EBS | Attached to one instance as a disk | Boot volumes, databases, low-latency I/O |
| File | EFS, FSx | Mounted by many instances at once | Shared content, lift-and-shift file workloads |
S3 essentials
Objects live in buckets with globally unique names. There are no real folders — slashes in a key are just characters the console displays as a hierarchy. A single object can be up to 5 TB, and anything over 5 GB must use multipart upload.
S3 Standard is designed for eleven nines of durability by storing redundantly across at least three AZs. Since 2020 it also provides strong read-after-write consistency, including for overwrites and listings — older material describing eventual consistency is out of date.
Storage classes
| Class | Retrieval | Right for |
|---|---|---|
| Standard | Immediate | Frequently accessed data |
| Intelligent-Tiering | Immediate | Unpredictable access — moves objects automatically |
| Standard-IA | Immediate, retrieval fee | Known-infrequent access, 30-day minimum |
| One Zone-IA | Immediate | Re-creatable data; lost if that AZ is lost |
| Glacier Instant | Immediate | Quarterly access at archive pricing |
| Glacier Flexible | Minutes to hours | Archives with occasional retrieval |
| Deep Archive | ~12 hours | Long-term compliance retention |
Protecting data
Versioning keeps every version, so a delete writes a marker rather than destroying data. It is the prerequisite for replication and for most recovery scenarios — but without a lifecycle rule expiring noncurrent versions, storage grows without bound.
Object Lock in compliance mode enforces write-once retention that not even the root user can shorten, which is what regulators and ransomware defences require. Governance mode allows a privileged override, so it is not equivalent.
Worth remembering
- S3 is object storage — flat keys, HTTP access, no file-system semantics.
- EBS attaches to one instance; EFS mounts on thousands.
- Storage classes have minimum durations and per-object overhead that can outweigh the saving.
Test it now
Storage-class and lifecycle economics are heavily tested.