The Storage Gateway service enables hybrid cloud backup by presenting local block storage that synchronizes with AWS cloud storage. For scenarios where all data must remain available locally while still backed up to AWS, the correct mode is gateway-stored volumes.

AWS documentation defines:

“Use stored volumes if you want to keep all your data locally while asynchronously backing up point-in-time snapshots to Amazon S3 for durable storage.”

These volumes expose an iSCSI interface compatible with POSIX file systems, allowing direct use by on-premises backup software.

Gateway-cached volumes (Option C) store primary data in AWS with limited local cache, violating the “all data must be available locally” requirement. Options A and B are object-based storage solutions, not compatible with POSIX or block-based backup applications.

Therefore, Option D fully satisfies CloudOps reliability and continuity best practices by ensuring local availability, cloud durability, and POSIX compatibility for backups.

References (AWS CloudOps Documents / Study Guide):

• AWS Certified CloudOps Engineer – Associate (SOA-C03) Exam Guide – Domain 2: Reliability and Business Continuity

• AWS Storage Gateway User Guide – Stored Volumes Overview

• AWS Well-Architected Framework – Reliability Pillar

• AWS Hybrid Cloud Storage Best Practices