[AWS] S3 Storage Classes and Versioning

S3 Storage Classes (Storage Tier) – cost, durability, and availability – can be changed manually or using lifecycle policies.

Link: https://aws.amazon.com/s3/storage-classes/

• Object Durability: The percentage over a one-year period that an object in S3 will not be lost.
• Object Availability: The percentage over a one-year period that an object in S3 will be accessible.

S3 Tiered Storage Classes

Storage classes can be modified on the fly.

• Lifecycle rules are added at a bucket level.
  • Lifecycle automatically moves objects between the different storage tiers.
  • You can add a rule to a bucket such as Standard -> Glacier -> Delete.
  • Automatic transition of object between storage classes.
  • Lifecycle rules can apply to buckets, prefixes, and tags. Also, they work with current or previous versions of an object.
  • Object must stay at least 30 days in S3 Standard before moving to IA or one zone IA. But you can transfer objects directly to Glacier at any time.

• Standard: default
  • 11 nines durability, 4 nines availability
  • Replicated in +AZs (redundant), no retrieval fee but most expensive base fee
• Standard Infrequent Access (Standard-IA)
  • Fast real-time access but less frequently, 3+ AZs replication
  • 30-day and 128 KB minimum charge, object retrieval fee
• One Zone IA
  • non-critical or reproducible data
  • reduced availability (99.5%), 1 AZ, 30-day and 128 KB minimum charge
• Glacier
  • long-term secure, durable archival, 3+ AZs
  • retrieval types
    • Expedited retrieval: 1-5 mins
    • Standard retrieval: 3-5 hours
    • Bulk retrieval: 5-12 hours with a large amount of data
  • 90-day and 40KB minimum charge, object retrieval fee
• Glacier Deep Archive
  • long-term cold backups, lowest cost
  • Retrieval time: 12 hours
  • 180-day and 40KB minimum charge, object retrieval fee
• Intelligent tiering: (for objects bigger than 128 kB)
  • for unknown or unpredictable access patterns
  • A minimum 30 days before transitioning to IA storage tiers.
  • After 30 days, objects that are not accessed are moved to the IA tier.

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S3 Versioning

When the versioning is enabled, any modification of an object generated a new version of the original object.

• Once enabled, S3 stores all versions of an object with previous permissions. It is a great backup tool.
• Version is per bucket and is disabled by default.
• Once the version is enabled on a bucket, it cannot be disabled – only suspended.

• AWS charges all versions of all objects.
• Older versions can be accessed using the object and a version ID.
• Specific versions can be deleted. (It is checked as “delete marker.”)
• Versioning integrates with Lifecycle rules.

• Versioning can use with MFA (Multi-Factor Authentication) Delete, which can provide additional security for accidental deletion or overwrite.

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S3 Performance

• Limits: 3,500 PUT/POST/DELETE operations per second, 5,500 GET requests per second per prefix.

• Introduce key randomness (random prefix) to spread load across multiple partitions.
  • Prefix is what is between the bucket name and the object name in URL (folders and subfolders).
  • You can get better performance by spreading the reads across different prefixes.

When you use SSE-KMS for encryption, KMS has some limits (KMS has a region-specific quota).

• Use multipart uploads (recommended over 100MB and required over 5GB) to increase upload performance.
• Use S3 Byte-range fetches: It parallelizes downloads by specifying byte ranges or download the partial amount of file.