An on-premises application needs backups to AWS but all backed-up data must remain available locally. The backup software can only write to POSIX-compatible block devices. Which AWS backup approach satisfies these constraints?

Gateway-stored volumes provide block storage to on-premises applications using iSCSI, while asynchronously backing up point-in-time snapshots to Amazon S3. This setup meets the requirement for local data availability and POSIX-compatible block device access for the backup software. S3 and S3 Glacier are object storage services, not block devices, so the backup tool cannot directly write to them. Gateway-cached volumes store primary data in S3 and cache frequently accessed data locally, which doesn't guarantee all data remains locally available for the backup tool in the same way gateway-stored volumes do.