S3 Intelligent-Tiering is a storage class that automatically reduces storage costs by moving data to the most cost-effective access tier based on access frequency. It has two access tiers: frequent access and infrequent access. Data is stored in the frequent access tier by default, and moved to the infrequent access tier after 30 consecutive days of no access. If the data is accessed again, it is moved back to the frequent access tier1. By using S3 Lifecycle rules to transition objects from S3 Standard to S3 Intelligent-Tiering, the solution can reduce S3 costs for data with unknown or changing access patterns.

A. Use S3 replication to transition infrequently accessed objects to S3 Standard-Infrequent Access (S3 Standard-IA). This solution will not meet the requirement of reducing S3 costs for data with unknown or changing access patterns, as S3 replication is a feature that copies objects across buckets or Regions for redundancy or compliance purposes. It does not automaticallymove objects to a different storage class based on access frequency2.

B. Use S3 Lifecycle rules to transition objects from S3 Standard to Standard-Infrequent Access (S3 Standard-IA). This solution will not meet the requirement of reducing S3 costs for data with unknown or changing access patterns, as S3 Standard-IA is a storage class that offers lowerstorage costs than S3 Standard, but charges a retrieval fee for accessing the data. It is suitable for long-lived and infrequently accessed data, not for data with changing access patterns1.

D. Use S3 Inventory to identify and transition objects that have not been accessed from S3 Stand-ard to S3 Intelligent-Tiering. This solution will not meet the requirement of reducingS3 costs for data with unknown or changing access patterns, as S3 Inventory is a feature that provides a report of the objects in a bucket and their metadata on a daily or weekly basis. It does not automatically move objects to a different storage class based on access frequency3.

Reference URL: https://aws.amazon.com/s3/storage-classes/intelligent-tiering/

S3 Intelligent-Tiering is the best solution for reducing S3 costs when the access pattern is unpredictable or changing. S3 Intelligent-Tiering automatically moves objects between two access tiers (frequent and infrequent) based on the access frequency, without any performance impact or retrieval fees. S3 Intelligent-Tiering also has an optional archive tier for objects that are rarely accessed. S3 Lifecycle rules can be used to transition objects from S3 Standard to S3 Intelligent-Tiering.

Reference URLs:

1 https://aws.amazon.com/s3/storage-classes/intelligent-tiering/

2 https://docs.aws.amazon.com/AmazonS3/latest/userguide/using-intelligent-tiering.html

3 https://docs.aws.amazon.com/AmazonS3/latest/userguide/intelligent-tiering-overview.html