An application runs across Linux EC2 instances in an Auto Scaling group. The instances are launched from a launch template and use gp3 EBS volumes for primary storage. The team needs all instances to access the same files with data consistency. Which solution will provide a shared, consistent file system for all instances?

Amazon EFS provides a scalable, fully managed, and highly available NFS file system that can be mounted by multiple EC2 instances concurrently, ensuring data consistency across all instances. Creating the EFS file system separately and then updating the launch template with user data to mount it is the correct operational procedure. Updating the Auto Scaling group to use this new launch template version will ensure all new instances automatically mount the EFS, and replacing older instances will bring them into compliance. Enabling Multi-Attach on EBS volumes is incorrect because Multi-Attach allows multiple instances to attach to a single Provisioned IOPS SSD (io1 or io2 Block Express) volume, but it does not provide a shared file system with data consistency for general-purpose use cases like gp3 volumes, and it requires a cluster-aware file system (like OCFS2 or GFS2) to prevent data corruption. Synchronizing data with a cron job is inefficient, complex, and prone to data inconsistencies and conflicts. Creating an EFS file system via a launch template user data is incorrect because EFS file systems are created independently and then mounted; they are not created on a per-instance basis through user data.