SAA-C03
Deep Dive
S3 has multiple storage tiers with different cost vs availability vs retrieval-time trade-offs. The exam presents scenarios with specific access patterns and asks for the most economical configuration.
| Storage Class | Approx. cost | Retrieval | Min duration | Ideal use |
|---|---|---|---|---|
| S3 Standard | $0.023/GB | Immediate (ms) | None | Frequently accessed data |
| S3 Standard-IA | $0.0125/GB + retrieval | Immediate (ms) | 30 days / 128KB | Backups, active DR |
| S3 One Zone-IA | $0.01/GB + retrieval | Immediate (ms) | 30 days / 128KB | Reproducible data (thumbnails) |
| Glacier Instant | $0.004/GB | Immediate (ms) | 90 days | Archives with urgent occasional access |
| Glacier Flexible | $0.0036/GB | 1-5 min / 3-5h | 90 days | Long-term backups, compliance |
| Glacier Deep Archive | $0.00099/GB | 12-48 hours | 180 days | 7-10 year retention, very rare access |
Minimum storage duration (common trap)
If you delete or transition an object before its minimum duration, you pay for the minimum anyway. Standard-IA: 30-day minimum. Glacier: 90 days. Deep Archive: 180 days.
One Zone-IA — when NOT to use it
One Zone-IA stores data in a single AZ. If that AZ has an outage, the data is lost. Only for reproducible data (generated thumbnails, transcoded media). Never for unique backups.
Lifecycle Rules automate the transition of objects between storage classes or their expiration. They're configured at the bucket level or by prefix/tag. Two types of actions: Transition and Expiration.
Transition Actions
Moves objects to a cheaper storage class after N days.
Expiration Actions
Automatically deletes objects after N days.
Transition order (can only go from "hot" to "cold")
You cannot transition in reverse (e.g. from Glacier to Standard-IA) with lifecycle — you must restore and re-upload.
Intelligent-Tiering automatically moves objects between tiers based on the actual access pattern. No retrieval fee. Monthly monitoring fee: ~$0.0025/1,000 objects.
Frequent Access
Accessed in the last 30 days. Cost = Standard.
Infrequent Access
Not accessed in 30 days. Automatic. Cost = Standard-IA.
Archive Instant Access
Not accessed in 90 days. Automatic. Instant retrieval.
Archive Access
Not accessed in 90-730 days. Optional. Retrieval in 3-5h.
Deep Archive Access
Not accessed in 180-730 days. Optional. Retrieval in 12h.
When to use Intelligent-Tiering vs Lifecycle
Intelligent-Tiering: variable or unknown access pattern. AWS decides automatically. No retrieval penalty.
Lifecycle: known and predictable access pattern (e.g. "last month's logs"). More economical when the pattern is fixed (no monitoring fee).
gp3 (General Purpose SSD)
$0.08/GB-month
3,000 baseline IOPS (free)
Cheaper than gp2 — IOPS and throughput are configured independently of size.
gp2 (General Purpose SSD)
$0.10/GB-month
3 IOPS/GB (min 100)
IOPS scale with size. For more IOPS you need a larger volume (or migrate to gp3).
io2 Block Express (Provisioned IOPS)
$0.125/GB + $0.065/IOPS
Up to 256,000 IOPS
For critical databases. Expensive but predictable. Multi-Attach supported.
st1 (Throughput Optimized HDD)
$0.045/GB-month
Not for IOPS — throughput
Big data, log processing. High sequential throughput. NOT a root volume.
sc1 (Cold HDD)
$0.015/GB-month
Minimal access
Cheapest EBS option. For cold data accessed rarely. NOT a root volume.
Ingress (into AWS)
Egress (out of AWS)
Free
Transfer cost optimization
Exam trap
Traffic between AZs in the same region has a cost ($0.01/GB each direction). To avoid it: keep instances in the same AZ as the ELB node (Cross-Zone LB disabled) or use VPC Gateway Endpoints to reach S3 from EC2 instead of a NAT Gateway.
Automatic transition pipeline: Standard → IA → Glacier → Deep Archive.
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Test what you just learned
A company stores 100 TB of application logs in S3 Standard. Logs from the last month are queried frequently for debugging; logs from 2-12 months old are queried rarely. Logs older than 1 year are never queried but must be retained for 7 years for compliance. What is the most cost-effective configuration?
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