Amazon S3 Glacier Archive Strategy - Storage Class Selection and Retrieval Options
Clarify the selection criteria for Instant Retrieval, Flexible Retrieval, and Deep Archive. This guide covers automatic tiering with lifecycle policies and compliance support with Vault Lock.
Overview of Glacier Storage Classes
S3 Glacier is a low-cost storage service designed for long-term archiving, offering three classes. Glacier Instant Retrieval provides millisecond access and is up to 68% cheaper than S3 Standard-IA. It is well suited for archiving medical images or press photos accessed roughly once per quarter. Glacier Flexible Retrieval (formerly S3 Glacier) offers three retrieval options: expedited (1-5 minutes), standard (3-5 hours), and bulk (5-12 hours). It is ideal for backup data accessed once or twice a year. Glacier Deep Archive is the lowest-cost storage class, with standard retrieval taking 12 hours and bulk retrieval taking 48 hours. It is best for compliance data that must be retained for 7-10 years due to regulatory requirements.
Automatic Tiering with Lifecycle Policies
S3 lifecycle policies allow you to automatically transition objects to different storage classes based on their age. A typical design transitions objects to Standard-IA after 30 days, to Glacier Flexible Retrieval after 90 days, and to Deep Archive after 365 days. Lifecycle policies can filter by prefix or tag, enabling different policies for different types of objects within a bucket. Enabling the Archive Access and Deep Archive Access tiers in S3 Intelligent-Tiering automatically transitions objects to Glacier-equivalent tiers based on access patterns. Unlike age-based lifecycle policies, this approach makes decisions based on actual access frequency, making it suitable for data with unpredictable access patterns.
Compliance and Vault Lock
Glacier Vault Lock applies a WORM policy to a vault, preventing deletion or modification of data once written. It enables the construction of tamper-proof archives that comply with financial regulations such as SEC Rule 17a-4 and FINRA. Once a Vault Lock policy is locked, it cannot be changed, so it is recommended to verify it in test mode before locking. S3 Object Lock provides similar WORM functionality but with object-level control, offering a choice between Governance mode (privileged users can override) and Compliance mode (no one can override). For a deeper understanding of Glacier, specialized books on Amazon are helpful.
Glacier Pricing Comparison
Glacier Instant Retrieval costs approximately $0.004 per GB per month with millisecond retrieval. Glacier Flexible Retrieval costs approximately $0.0036 per GB, with standard retrieval (3-5 hours) at approximately $0.01 per GB and expedited retrieval (1-5 minutes) at approximately $0.03 per GB. Glacier Deep Archive is the cheapest at approximately $0.00099 per GB but requires 12 hours for standard retrieval. Minimum storage durations are 90 days for Instant Retrieval, 90 days for Flexible Retrieval, and 180 days for Deep Archive. Early deletion incurs charges for the remaining duration. When designing automatic tiering with lifecycle policies, it is important to account for these minimum storage durations.
Summary
Glacier is an archive storage service that stores infrequently accessed data at extremely low cost. Choose among the three classes - Instant Retrieval (millisecond access), Flexible Retrieval (hours), and Deep Archive (12 hours) - based on access frequency and retrieval time requirements. Configure automatic transitions with S3 lifecycle rules and achieve WORM compliance with Vault Lock.