The seven classes at a glance
All classes offer the same 11 nines (99.999999999%) durability. They differ in availability, retrieval speed, minimum storage duration, and cost.
| Class | Best for | Retrieval | Min duration |
|---|---|---|---|
| S3 Standard | Frequently accessed data | Milliseconds | None |
| Intelligent-Tiering | Unknown/changing access patterns (auto-moves tiers) | Milliseconds | None |
| Standard-IA | Infrequent access, rapid when needed | Milliseconds | 30 days |
| One Zone-IA | Infrequent, re-creatable data (single AZ) | Milliseconds | 30 days |
| Glacier Instant Retrieval | Archive needing instant access | Milliseconds | 90 days |
| Glacier Flexible Retrieval | Archive, retrieval in minutes–hours | 1 min – 12 hrs | 90 days |
| Glacier Deep Archive | Long-term archive, lowest cost | 12 – 48 hrs | 180 days |
Resilience: how many Availability Zones
- Every class stores data across ≥ 3 Availability Zones — except One Zone-IA, which uses a single AZ. That makes it ~20% cheaper than Standard-IA but vulnerable if that AZ is lost.
- Use One Zone-IA only for data you can re-create (e.g. thumbnails, secondary copies).
How the costs trade off
As you move down the list, storage gets cheaper but retrieval gets slower and pricier, and minimum-duration charges grow. IA and Glacier classes add a per-GB retrieval fee and bill early-deletion if you remove objects before the minimum duration.
Intelligent-Tiering charges a small monitoring fee per object but no retrieval fees — ideal when access patterns are unpredictable.
Exam traps
- One Zone-IA for critical data. One AZ = lower availability; don't use it for irreplaceable data.
- Forgetting minimum-duration charges. Deleting Standard-IA objects before 30 days still bills 30 days.
- Glacier Instant vs Flexible. Instant = millisecond retrieval; Flexible = minutes to hours.
- Assuming Glacier is a separate service. It's a set of S3 storage classes.
Test yourself
4 quick questions — tap an answer to check it instantly. Nothing is sent anywhere.
1. Which storage class stores data in a single Availability Zone?
2. Lowest-cost class for long-term archive with ~12-hour retrieval?
3. Best class when access patterns are unknown or changing?
4. Minimum storage duration for Standard-IA?
Sources
- Amazon Web Services — S3 Storage Classes.
- AWS, Amazon S3 User Guide — using storage classes.
Reference summary only. "AWS" is a trademark of Amazon. Confirm current details and pricing in the official AWS documentation.