Answer: Amazon Elastic File System (Amazon EFS) with multiple mount targets

## Explanation Amazon Elastic File System (Amazon EFS) is the correct solution because it meets all the specified requirements: 1. **Highly available and scalable**: EFS is a fully managed, highly available file storage service that automatically scales up or down as files are added or removed. 2. **Functions as a file system**: EFS provides a file system interface, unlike EBS which is block storage. 3. **Mountable by multiple Linux instances**: EFS can be mounted concurrently by thousands of EC2 instances across multiple Availability Zones. 4. **Accessible from on-premises**: With a Site-to-Site VPN connection, on-premises servers can mount EFS file systems using standard NFS protocols. 5. **No minimum size requirements**: EFS has no minimum storage requirement and you pay only for what you use. 6. **Multiple mount targets**: For high availability across multiple Availability Zones, EFS should have mount targets in each AZ where instances need access. **Why other options are incorrect**: - **A. Amazon FSx Multi-AZ deployments**: While FSx is a file system, it's typically used for Windows (SMB) or Lustre (high-performance computing), not the best fit for general Linux file sharing. - **B. Amazon EBS Multi-Attach volumes**: EBS is block storage, not a file system, and while Multi-Attach allows multiple instances to attach to a volume, they need to use a clustered file system, and it doesn't support on-premises access. - **D. EFS with a single mount target**: A single mount target creates a single point of failure and doesn't provide high availability across multiple AZs. **Key AWS Services Comparison**: - **EFS**: Network File System (NFS) for Linux workloads, multi-AZ by default, accessible from on-premises via VPN/Direct Connect - **EBS**: Block storage for single EC2 instances (except Multi-Attach), not accessible from on-premises - **FSx**: Managed file services for Windows (SMB) or Lustre (HPC)

Author: LeetQuiz Editorial Team