What is the MOST scalable storage solution to fulfill this requirement?
Connect a large Amazon EBS volume to multiple instances and schedule snapshots.
Deploy Amazon EFS in the VPC and create mount targets in multiple subnets.
Launch an EC2 instance and share data using SMB/CIFS or NFS.
Deploy an AWS Storage Gateway cached volume on Amazon EC2.
Explanations:
Amazon EBS volumes can only be attached to a single EC2 instance at a time, making it unsuitable for sharing data across multiple instances in different Availability Zones. While snapshots can help with backups, they do not facilitate simultaneous access to data.
Amazon EFS (Elastic File System) is designed for high scalability and can be mounted by multiple EC2 instances across different Availability Zones. It automatically scales as data is added, making it an ideal solution for the anticipated growth to tens of terabytes.
Sharing data using SMB/CIFS or NFS through a single EC2 instance creates a single point of failure and does not offer the scalability or redundancy needed for an application requiring multiple Availability Zone access. It can also become a bottleneck as data grows.
AWS Storage Gateway cached volumes are primarily used to provide a seamless integration of on-premises environments with AWS cloud storage and do not provide the direct file system interface needed for multiple EC2 instances to share data efficiently across Availability Zones.