S3 Performance and Resilience

Question 1

What are the 5 Storage Classes in S3?

Answer 1

o All objects within a S3 bucket use a storage class, also known as storage tier. Storage classes influence the cost, durability, availability for objects in S3. Storage classes can be changed manually or using lifecycle policies
o Standard: Default, all-purpose storage or when usage is unknown. 99.999999999% (11 nines) durability and 4 nines availability, replicated in 3+ AZs, no minimum object size or retrieval fee
o Standard Infrequent Access (Standard-IA): For objects where real-time access is required, but infrequent. 99.9% availability, 3+ AZs replication, cheaper than standard; 30-day and 128KB minimum charges and object retrieval fee
o One-Zone IA: non-critical and/or reproducible objects; 99.5% availability, 1 AZ replication, cheaper than Standard-IA
o Glacier: Long-term archival storage (warm or cold backups); retrieval could take minutes or hours (faster = higher cost); 3+ AZs replication, 90-day and 40KB minimum charge and retrieval
o Glacier Deep Archive: Long-term archival (cold backups); 180-day and 40KB minimum charge and retrieval; Longer retrieval (hours), but cheaper than Glacier, replacement for tape-style storage

Question 2

What are Lifecycle Policies?

Answer 2

o Storage Classes can be controlled via lifeycle rules, which allow for the automated transition of objects between storage classes, or in certain cases allow for the expiration of objects that are no longer required
o Rules are added at bucket level, and can be enabled or disabled based on business requirements
o Instead of transitioning between tiers, objects can be configured to expire after certain time periods (they are then deleted from the bucket)
o When objects move to Glacier, they remain inside S3, are managed from S3, but are physically stored in Glacier

Question 3

What is Intelligent Tiering?

Answer 3

o	Intelligent Tiering is a special type of storage class, designed for unknown or unpredictable access patterns. It moves objects automatically between the frequent and infrequent access tiers, based on 30-days no access; it has a monthly automation and monitoring fee, but no retrieval costs and no fee for moving data between classes
o	Objects smaller than 128KB cannot be transitioned into INTELLIGENT_TIERING. Objects much be in the original storage class for a minimum of 30 days before being transitioned to either of the IA storage tiers

Question 4

What is Cross Region Replication?

Answer 4

o S3 cross-region replication (S3 CRR) is a feature that can be enabled on S3 buckets allowing one-way replication of data from a source bucket to a destination bucket in another region
o Replicated objects, by default, keep their Storage Class, Object Name (key), Owner and Object Permission
o Replication configuration is applied to the source bucket, and to do so requires versioning to be enabled on both buckets. Replication requires an IAM role with permissions to replicate objects. With the replication configuration, it is possible to override the storage class and object permissions as they are written to the destination
o The following are excluded from replication:
 System actions (lifecycle events)
 Any existing objects from before replication is enabled
 SSE-C encrypted objects – only SSE-S3 and (if enabled) KMS encrypted objects are supported