A company runs a self-managed database on Amazon EC2 with Amazon Elastic Block Store (Amazon EBS) storage totaling 350 TB. The company takes daily EBS snapshots and retains them for 1 month. Daily change rate is 5% of the volumes. New regulations require keeping monthly snapshots for 7 years. The company wants to update its backup strategy to comply and ensure data availability with minimal administrative effort and with the lowest cost. Which solution meets these requirements MOST cost-effectively?

The most cost-effective solution involves using a tiered storage strategy. Keeping daily snapshots in the EBS standard tier for 1 month is appropriate for recent, frequently accessed backups. For long-term, infrequently accessed archives like monthly snapshots for 7 years, Amazon S3 Glacier Deep Archive is significantly more cost-effective than EBS Snapshots Archive or the EBS standard tier. EBS snapshots are incremental, meaning only changed blocks are stored, which optimizes storage. Copying monthly snapshots to Glacier Deep Archive leverages its extremely low cost for long-term retention, meeting regulatory requirements with minimal administrative effort as it's a managed service. The other options are less cost-effective: Using EBS Snapshots Archive for 7 years is more expensive than Glacier Deep Archive for this retention period. Keeping monthly snapshots in the EBS standard tier for 7 years would be prohibitively expensive due to the higher per-GB cost compared to archive tiers. Using EBS direct APIs to store snapshots in S3 Infrequent Access is more complex to manage and potentially more expensive than using integrated EBS snapshot archiving features.