Amazon S3 Glacier
Amazon S3 Glacier is a secure, durable, and extremely low-cost cloud storage service for data archiving and long-term backup. It is designed to deliver 99.999999999% (11 9s) durability.
Storage Classes
Gone are the days of a single "Glacier". It is now a set of S3 storage classes:
- S3 Glacier Instant Retrieval:
- Retrieval Time: Milliseconds.
- Use Case: Archive data that needs immediate access (e.g., medical images, news media).
- Costs: Higher storage cost than other Glacier tiers, but cheaper retrieval.
- S3 Glacier Flexible Retrieval (Formerly just S3 Glacier):
- Retrieval Time:
- Expedited: 1-5 minutes (expensive).
- Standard: 3-5 hours.
- Bulk: 5-12 hours (free).
- Use Case: Backups, Disaster Recovery, offsite data storage.
- S3 Glacier Deep Archive:
- Retrieval Time:
- Standard: 12 hours.
- Bulk: 48 hours.
- Use Case: Long-term retention (7-10 years), Compliance (Tax records, Legal), Tape replacement.
- Costs: Lowest cost storage class in AWS.
Key Concepts
- Vaults & Archives (Legacy Model): Originally Glacier used "Vaults" instead of Buckets and "Archives" instead of Objects. This API still exists but using S3 rules to transition data to Glacier classes is preferred.
- Vault Lock: Enforces compliance via WORM (Write Once Read Many) policy. you can lock a vault so data cannot be deleted or modified for a set period.
Exam Tips
- Low Cost + Minutes/Hours retrieval: S3 Glacier Flexible Retrieval.
- Lowest Cost + 12-48h retrieval: S3 Glacier Deep Archive.
- Immediate Access + Archive: S3 Glacier Instant Retrieval.
- Minimum Storage Duration:
- Flexible Retrieval: 90 days.
- Deep Archive: 180 days.
- Deleting before this incurs an early deletion fee.
Common Use Cases
- Regulatory compliance archiving (HIPAA, FINRA).
- Digital media asset preservation.
- Backup and restore replacement.