AWS Storage Optimization
AWS Whitepaper

Conclusion

Storage optimization is the ongoing process of evaluating changes in data storage usage and needs and choosing the most cost effective and appropriate AWS storage option. For object stores, you want to implement Amazon S3 lifecycle policies to automatically move data to cheaper storage tiers as data is accessed less frequently. For Amazon EBS block stores, monitor your storage usage and resize underutilized (or overutilized) volumes. You also want to delete unattached volumes and stale Amazon EBS snapshots so that you’re not paying for unused resources. You can streamline the process of storage optimization by setting up a monthly schedule for this task and taking advantage of the powerful tools by AWS and third-party vendors to monitor storage costs and evaluate volume usage.