| Class | Cost (per GB/month) | Retrieval Cost | Best For |
|---|---|---|---|
| Standard | ~$0.023 | None | Frequently accessed |
| Intelligent-Tiering | ~$0.023 + monitoring fee | None | Unknown access patterns |
| Standard-IA | ~$0.0125 | Per GB retrieved | Infrequent but rapid access |
| One Zone-IA | ~$0.01 | Per GB retrieved | Non-critical infrequent data |
| Glacier Instant | ~$0.004 | Per GB retrieved | Archive, millisecond access |
| Glacier Flexible | ~$0.0036 | Per retrieval request | Archive, minutes-hours |
| Glacier Deep Archive | ~$0.00099 | Per retrieval request | Long-term archive, 12+ hours |
Automate transitions between storage classes and object expiration.
Create an S3 bucket with lifecycle policies to automatically transition and expire objects.
10 minutes
Step 1: Create an S3 bucket
BUCKET="saa-lifecycle-$(date +%s)"
aws s3api create-bucket --bucket $BUCKET --region us-east-1
Step 2: Apply a lifecycle policy
aws s3api put-bucket-lifecycle-configuration --bucket $BUCKET \
--lifecycle-configuration '{
"Rules": [
{
"ID": "TransitionToIA",
"Status": "Enabled",
"Filter": {"Prefix": "logs/"},
"Transitions": [
{"Days": 30, "StorageClass": "STANDARD_IA"},
{"Days": 90, "StorageClass": "GLACIER"}
],
"Expiration": {"Days": 365}
}
]
}'
Step 3: Verify the lifecycle configuration
aws s3api get-bucket-lifecycle-configuration --bucket $BUCKET
aws s3 rb s3://$BUCKET --force
| # | Question | Answer |
|---|---|---|
| 1 | Cheapest S3 storage class? | Glacier Deep Archive (~$0.00099/GB/month) |
| 2 | Min days before transitioning Standard to IA? | 30 days |
| 3 | What is S3 Intelligent-Tiering? | Auto-moves objects between access tiers based on usage patterns |
| 4 | What is AWS Budgets? | Set custom cost/usage budgets with alerts |
| 5 | gp3 vs gp2 cost? | gp3 is 20% cheaper with configurable IOPS |
| 6 | What are cost allocation tags? | Tags for tracking costs by project, team, or environment |
| 7 | What is Requester Pays? | Requester pays for data transfer and requests instead of bucket owner |
| 8 | What is DLM? | Data Lifecycle Manager — automates EBS snapshot creation/deletion |
| 9 | What does Cost Explorer do? | Visualize spending patterns and forecast future costs |
| 10 | What is CUR? | Cost and Usage Report — most detailed cost data delivered to S3 |
A company stores application logs in S3 Standard. Logs are accessed frequently for the first 30 days, occasionally for the next 60 days, and rarely after that. They must be retained for 1 year. Which lifecycle policy minimizes cost?
Correct: B
This lifecycle matches the access pattern: Standard for frequent access (30 days), Standard-IA for occasional access (30-90 days), Glacier for rare access (90-365 days), then delete. Keeping in Standard is expensive. Deep Archive after 30 days would make occasional access slow and costly. Intelligent-Tiering works but the known pattern makes explicit transitions more cost-effective.
Domain: 4 — Design Cost-Optimized Architectures Task: 4.1
A company has hundreds of unattached EBS volumes across multiple accounts. How should they identify and reduce this waste?
Correct: D
Both AWS Config (with rules for unattached volumes) and Trusted Advisor (which checks for idle resources including unattached EBS volumes) can identify this waste. Cost Explorer shows spending but does not specifically identify unattached volumes.
Domain: 4 — Design Cost-Optimized Architectures Task: 4.1
A company wants to archive compliance data that must be retained for 7 years but is almost never accessed. Retrieval within 12 hours is acceptable. Which storage class is most cost-effective?
Correct: C
Glacier Deep Archive is the cheapest storage class and supports retrieval within 12 hours (standard retrieval). Standard-IA and One Zone-IA are more expensive for rarely accessed data. Glacier Flexible Retrieval is cheaper than IA but more expensive than Deep Archive.
Domain: 4 — Design Cost-Optimized Architectures Task: 4.1
A company migrated to gp2 EBS volumes but wants to reduce storage costs without changing performance. What should they do?
Correct: B
gp3 volumes are 20% cheaper than gp2 with the same or better baseline performance. IOPS and throughput can be independently configured. st1 is HDD and would change performance characteristics. Encryption does not reduce cost. Snapshots are for backup, not active storage.
Domain: 4 — Design Cost-Optimized Architectures Task: 4.1
A company hosts a public dataset on S3 and wants to avoid paying for data transfer when external users download the data. Which S3 feature should they enable?
Correct: B
Requester Pays shifts the cost of data transfer and request charges to the requester instead of the bucket owner. Transfer Acceleration speeds up uploads but does not shift costs. CRR creates copies in another region. CloudFront caches content but the bucket owner still pays for origin requests.
Domain: 4 — Design Cost-Optimized Architectures Task: 4.1