Amazon EFS (Recommended for most shared file workloads): Provides a fully managed Network File System (NFS) that can be mounted simultaneously by thousands of EC2 instances across multiple Availability Zones. It handles scaling and high availability automatically.

Amazon FSx: If the workload requires specific file systems like FSx for Windows File Server (for Windows environments using SMB) or FSx for Lustre (for high-performance computing/HPC), these also provide fully managed shared storage for multiple instances.

Amazon EBS Multi-Attach: An alternative only if they require block-level storage rather than a file system. It allows a single Provisioned IOPS SSD (io1 or io2) to be attached to up to 16 EC2 instances simultaneously, but only within the same Availability Zone and requires a cluster-aware file system to prevent data corruption.